It doesn't make much sense to classify the ME2 and ME3 galaxy map stuff as time fillers. They don't actually take much time -- about an hour to scan everything in ME3, for instance. I'm assuming basic competence, of course.
The scanning / fetching in ME3 would have been a whole lot easier were it not for the fact that various clusters appeared on the map little by little throughout the game. Since you can't scan an entire cluster in one go without attracting reapers, and the game doesn't mark the areas you've already scanned (and I've no interest in keeping notes), I'd pull out a list detailing the locations of the goodies every time more clusters popped up on the map. The concept was sound, imo, but the execution left a lot to be desired.
I don't know about resource scanning in ME2, though.
A single playthrough was enough to convince me to hack my save on subsequent games.
Enjoyed it that much, did ya?

ME2 cured me of my lifelong completionist tendencies. I don't bother with a lot of the available upgrades.