That might be possible, but is it likely? A knight is basically a medieval super-soldier: an individual with a huge amount of ongoing personal+state investment going into their ability to project power on the field.
Even if they're also a feudal lord who lives within their own holdings (and therefore someone who's not beholden to anyone around them, only to a distant king) everyone working for them is putting a lot of work into keeping the knight's equipment, their horse, etc. maintained and ready to go.
Wouldn't those same people push the knight themselves — for their own sakes! — to stay fit, as another kind of "maintenance"? Wouldn't there be mass resentment within a lazy knight's power structure, that would lead to said power structure toppling or mutiny-ing?
As for incompetent knights, I'm genuinely confused: how did they survive in the role for any length of time? (Especially when the only talent pool they would have to recruit underlings from are the very same people they're oppressing. I always figured competence at protecting the outlying villages—where everyone's families live—during invasion, was kinda the reason anyone bothered to work for them at all, rather than towns responding to recruitment attempts exactly the same as invasion attempts, with stoning, boiling oil from the rooftops, etc.)
The villagers, on the other hand, are used to invaders coming through. Their condition is likely to remain poor either way: The knight is more likely to come through after something happened, rather than preventing it from happening. Most of the daily decision making is up to the community.
The knight's recruitment efforts can always come with the promise of gaining wealth and status, which will always encourage some young folks, even if the knight is a bad boss who plans no real rewards. Records that uncover his lies are hard to acquire and most of what you learn will come from rumor instead.
Not all knights saw that much action. I agree though that they had strong incentives, besides survival in battle, to be at least defensibly competent.
As to those incentives -- they had a multi-generation arrangement with the sovereign: to supply a certain number of mounted men when he called for it, maybe determined by the size of landlord they were, and in return the king let them keep dominating economic activity in their usually-rural area. The knight held the purse strings and could extract as much as he felt prudent from his tenants (farmers etc).
But the knight would employ Men-at-Arms. These were the guys with what we think of today as 'Knight Skills,' but no land/title/purse. They'd be taken care of, and they'd definitely try to keep their boss alive. Or sometimes an older knight might send the required men without going himself. (This varies a lot by time period of course).
So on the one hand, they didn't have to do superhero stuff if they didn't want to.
On the other hand -- their whole reason to exist was intensely martial; the structure of society reflected the fact that folks riding horse-tanks dominated all of civilization. There were good reasons for someone with a coveted horse-tank position to, yes, be able to be ride, be at least minimally competent, and show up to risk their lives when the king calls for it, or else risk losing their privileged position.
> the reason anyone bothered to work for them at all, rather than towns responding to recruitment attempts exactly the same as invasion attempts, with stoning, boiling oil from the rooftops, etc
Well, the knight owned the siege-proof fortresses in the area; that's one of those things they did well in feudal times, picking geographical strong points for fortresses.
The knight also owned the town people lived in too, the farms, houses, etc. His family got them way back when kings started deciding that they didn't want the town to send 5 random foot soldiers when he called -- he'd rather have 1 professional, well-equipped horseman with mail, shield, lance etc, and if you could make that happen he'd just give you your neighbor's stuff to keep making it happen in perpetuity.
Most knights didn't fight often - if at all. Even when called upon they could just supply another person instead of themselves.
More interesting questions are:
Was the average knight fat?
How common were the?
How effective were fat/incompetent knights on the battlefield?
This isn't really correct. Most knights didn't have a huge incomes (if they did they would become Lords).
A Knight wasn't a military position - it was primarily a class and status designation, which came with some military obligations. These could be met by supplying another person to your lord to do the fighting for you.
Often a Knight would supply their lord with their younger son for example, since their older son would be the heir.
To become a knight in the medieval times in the UK you needed an income of 40 pounds a year[1] which converts to around 30,000 pounds/year these days.[2]
> Wouldn't there be mass resentment within a lazy knight's power structure, that would lead to said power structure toppling or mutiny-ing?
Yes, indeed peasant revolts were a thing. And a lot of most knights "fighting" involved hunting down rebellious peasants armed with sticks.
[1] https://www.quora.com/Were-Medieval-English-knights-wealthy-...
[2] https://www.nationalarchives.gov.uk/currency-converter/#curr...
On top of that a knight would have eaten a lot more fat, meat, and vegetables than a peasant, who would have lived almost entirely on bread. This wouldn’t have left the peasant totally protein-starved because it was bread made from whole grains, but a knight would have been getting much better returns on their exercise throughout life due to their more varied diet.
I believe the average member of the House of Commons was visibly shorter than the members of the House of Lords at least through WWII. Certainly Americans were obviously taller than Europeans until after WWII. Even American slaves were taller and children were generally malnourished until about seven when they became capable of working. Adult height seems to have been unaffected reflecting just how rich the US was comparatively. Complete unfeeling bastards didn’t malnourish children enough to do permanent damage.
The below article makes mention of a fact that may complicate things though - big strong slaves were worth more. Presumably slave owners had this in mind so had an ulterior motive for feeding slaves better.
It’s one bleak subject.
https://www.researchgate.net/publication/11718681_The_Height...
Very bleak, but slave owners had a large economic incentive to make sure their slaves were fit for work (although that didn't cause qualms on other, more brutal forms of mistreatment). The only way they treated them well was in providing food, but that wasn't due to kindness but more from the same motivation to feed a team of draft horses well. It's tough reading, but some of the ledgers kept by plantation owners really drive the point home that they viewed slaves more akin to livestock than people. And they somehow justified what they were doing as christian and moral.
I found this interesting article while looking:
Heights across the Last 2,000 Years in England: https://oro.open.ac.uk/53774/3/53774.pdf
> Floud et al. also showed that men who grew up in urban areas were shorter than men who grew up in rural areas, and that there were significant differences in the heights of men and boys from different socioeconomic backgrounds. At the beginning of the nineteenth century, 14-year-old boys attending the Royal Military Academy at Sandhurst were nearly six inches taller than their counterparts in the Marine Society
https://core.ac.uk/download/pdf/6876106.pdf (bottom of page 101).
"no penny, pullets for to buy,
Nor neither geese nor pigs · but two green cheeses,
A few curds and cream · and an oaten cake"
Working in the field all day is not the same as training specifically for combat whole day. And nutrition is massively important for muscle building.
If it’s a particular lazy knight that enjoys too much food, well.
Would be an interesting overlap of nutrition vs fitness vs indulgence.