It's decent enough to consider it, I'll give you that.
Something worth adding, I think:
I mainly play smaller games (like ≤ 10 GB, often below 5 GB at that), with few bigger ones in the mix, which is why I even considered this method.
Also back when GOG Galaxy was being introduced, GOG had fewer big games, I think. If not then it's that I lean towards smaller and older games in general.