I found a report someone compiled with released fight night weights for fighters and what they weighed in at on the scale. It has the fighter, event, weigh in weight, and fight night weight.
It seems the average percent put back on is 15%. It should be capped at 10% but that is an arbitrary number obviously.
Interesting that Jon Jones is at 18.5% which means out of camp he is closer to 230lbs. Chiesa is 188 on fight night as well which is insane considering he was starving himself to get to 155lbs.