I don't, LFP batteries are quite resilient. 80% -> 20% is a usability nightmare nobody with a $50k vehicle should accept. My Ioniq (first gen) doesn't even have an LFP battery and is optimized for 100% -> 13%, maybe even 100% -> 10% (turtle mode starts at 5%). Still at 100% SOH after three years.

Way more important for battery life is the charging rate (again, LFP are more resilient there too). Which wouldn't be an issue for grid use.

I think you do. If you drove 10 miles and recharged, you wouldn't consider that a "cycle". You could do that 100k times (probably more), but no one would say the battery cycle life is 100k.

I mean I didn’t count in 0.6 cycles per discharge. My battery does 0.9-0.95 cycles usually.

Is that how it works? Can I just charge every night, even if I've only driven a few miles, with no more wear on my battery than if I did full cycle charges? My vague impression is "no", but I really have no idea.

It is, with lithium, basically no different to go from 80%->20%->80% once or from 80%->75%->80% twelve times.

The only complicating issue is calendar life of the battery when it is above 80%. Over time a battery loses capacity just because it exists, which I'm calling calendar life. The closer your battery is to 100% the calendar life decreases at a roughly quadratic curve (a battery at 80% has about 1/8 the calendar life loss of one at 100%). AKA you lose 8x more capacity per year at 100% than 80%. Temperature has a similar effect above room temperature or so.

So if your frequent charges keep the battery above 80%, that would reduce calendar life (increase capacity loss per year) on its own. LFP has far greater calendar life than lipo, but also cycle life too, so I think it's just as important to keep your EV at 80% or below, whenever convenient, regardless of chemistry, unless your usage will cause cycle life to end the battery usefulness before calendar life is significant; i.e. multiple full cycles per day. But also at multiple full cycles per day you probably won't spend much time above 80% even when charging to 100%.

Ah, to summarize, I'll repeat my simple advice: I think it's important to keep your EV at 80% or below, whenever convenient.