it doesn't seem like the recipient's degree of training progress makes much difference since Gohan and Kuririn ended up in relatively the same ballpark despite Kuririn training for many years while Gohan only trained for about a year in his life, and Gohan obviously had incomparably greater potential. This power up just seems to be a multiplier if anything. Would be nice it we knew what the power boost was for Dende so we'd have more information and whether Nail even got his potential unlocked by the molestation master, but the evidence seems to support that as long as you have the potential to become like 7-8 times stronger, that is generally the boost the unlock gives. The Yamcha sidestory manga seems to contradict this somewhat with Yamcha only ending up "over 10,000" (same ballpark as Kuririn from the unlock) even though he got the unlock and then trained with Nail for months, but that's written by another author.