MonstaMunch: Being new to using Steam and GG I was wondering the same thing.
It might be a lot to ask, but would it be possible for someone who knows about such things to make a list of sales that usually happen, with approximate dates (like, Christmas Sales - December)? I'm going to try not to buy anything that isn't on sale, and that might be easier to force myself into if I know there's another sale just around the corner :)
From my experience with GOG for more than a year.
Sales on GOG:
First and third wednesday in the month: one game for 50-60% discount.
Every weekend if there are no other big announcements going on: 3-6 games for 40-60% discount.
Summer sale: 2-3 weeks in july about half the catalogue with 30-50% discount.
Christmas sale: approx. one week before christmas til start of january virtually the whole catalogue for 50%.
Rare but happens: Permanent price drops for older games.
That can be expected for this year again.
I too only bought games on sale lately. The backlog is too huge not to wait with wishlisted games. After all I might never be able to play them.