I was a combo of both. I would build the thing one time when it was brand new. It was a good way of learning how some pieces could be combined and be used in designs. After that, all the pieces got placed into big buckets for later assembly into whatever. I've never had a lego "build" last longer than a few days.

I think I treated Lego instruction books a bit as my bible. Thou shalt built this, at least once. Most of my creativity was in composition: I would built a city out of all those more or less built-to-instruction sets, and would overhaul said city every few months or so. Road plates would have sidewalks, roads with directions, that I would type and print on a computer, rail, preferable with a higher bridge somewhere every time. Once the whole city was built up and complete (no space left empty), I'd take it all away and compose a new city.

Man, we do both in my house.

When I was a kid, I mostly had pile-of-legos and not sets. I did very little following of the directions.

My kids *love* just messing around with piles of LEGO (and even Duplo) and making their own creations: mostly weapons. And they also love working on the 3000 piece crazy-complicated sets, presorting everything and figuring out where to put each piece step by step.

There's a whole lot of creative, unstructured play (not really heading towards mastery of sculpting or design), and a whole lot of concentrating replicating a model. It'd be kind of neat if they'd decide to do something inbetween.