The frequencies and amounts are really just suggestions --how often, and how much you feed per meal, really depends on a lot of things. For example: a skinny 10 year old skink should maybe be offered food every other day or more, and it may be good to let him eat however much he'll eat, whereas a 4 month old skink may not eat anything if he's offered a meal every other day, but will eat everything if you feed him every 3-4 days.
It all depends, and it can depend on a lot of things.
If your skink is at a good, healthy weight and in good condition, and has been eating whatever you offer him, it may be less stressful for you both

if you go from every other day to feeding every 3rd day. And, at least initially, maybe offer him more than he'll finish at each feeding. If he starts to only nibble or not eat at all at some feedings, then that may be your cue to offer him less in each meal, or to stretch the feedings out to every 4th day.