I don't usually do test blocks, but I often make more blocks than I need so I can pick the best of the bunch and toss out the "turkeys". I don't actually toss them out, they just end up as part of a crazy quilt down the road.
I like impromptu sewing - I'll start stitching things together without any sort of a plan at all, just a vague idea that it'll end up in a crazy quilt. It's a marvelous way for me to de-stress. And I love crazy quilts - I like how they look but most of all I enjoy the in-the-moment creativity of putting them together.