I was probably 8 or 9. From that point on, fuck it, they all go in one big box. My brothers and I would compete to see who could find the most valuable pieces. Mostly treasure chest coins, little gems, and basically anything translucent qualified - transparent single stud pieces, cone pieces, and lightsaber beams were very high value, since one could not build a respectable Lego sci-fi arsenal without all of them.
When I built Titantic last year (first Lego I'd done in maybe 30 years) it was split out over dozens of small bags, and all the parts you'd need for one section would be in that one bag with no more than, say, 200 pieces in it. Often there's be a smaller bag inside for holding the 1x1 stuff.
So I built the whole thing with two tupperware containers..one decent size square "bowl" and s much smaller one for the tiny stuff.
Killed a month off and on putting that thing together. I was recovering from foot surgery so stuck in bed.
Luckily, the Titanic actually builds as 6 sections, with 3 pairs that join more or less permanently, while there are then a couple of pins and rods that hold the whole thing together (along with a rather clever tensioning gear... the main lines are there as strings, and do hang in a true catenary. )
So each of the 6 sections I basically built on a hardback book.
A few build pics:
Made for a very doable build, even given pretty hefty physical limitations.
He is very fortunate to be part of a reasonably affluent family, so he had like 6 60-liter boxes full of assorted Lego.
We would spill a couple at a time (who am I kidding we spilled all of them) on the floor, when the flow of pieces stopped, the game was on! So many arguments about the nature of the simple shapes, like "oh no this isn't a blue lightsaber, it is a cylinder of pure diamond!"
