I make stuff with the kids for them to play with quite a bit. The lifecycle of our legos usually goes like this:
1. Build set
2. Play with it until disaster strikes and it gets disintegrated.
3. Maaaybe salvage it before mom gets frustrated with parts lying around the house where they should and dumps it into parts bin. If so, go back to step 2, otherwise
4. Lego set parts get recycled into building something else cool.
We don't generally care about matching colors or any of that. They just want stuff they can put their little lego guys in a drive/fly/float around in:
For nostalgia, here's some stuff they made with limited old school pieces at my mom's house: