It is my understanding that Palma are on a work to rule, so whilst the -5/+10 could usually be used by the pilots, at Palma and Arrecife they will not let you depart -5 or +10 at your convenience, only theirs.
The upshot is many times I have had to call for push way too early with the fake 15 or 25 minute taxi time or whatever fiction they come up with, then waited at the hold with two burning and turning for 10 mins waiting for the exact slot time to arrive.
I have asked them and they tell you the -5/+10 is for them and not for us. Either way I hate flying to PMI with a passion.