I suppose it depends on:

- How many patches you receive

- How easy it is/long it takes to distinguish the good from the garbage

You're assuming the other 70-80% is actually good. It's not, there's a whole spectrum between "junk" and "good". A whole bunch of this stuff is "technically correct, technically even a security issue, but also just plainly not of actual importance".

You get free meals, 70-80% of them tasty on different degrees, and the rest burnt. That's OK because free meals, right? Except the small letters say you have to eat 300 meals a day.