I hadn't drawn in a while and needed a page to just scribble on for a bit to get my wrist loosened up... also to get my brain loosened up. I definitely recommend doing warm ups before you sit down to draw that super cool idea you have. Get the junk out on a junk page. If that junk page ends up being super cool, great! But if not, you don't waste too much brain power just scribbling around and instead you get nice and warmed up for that super cool idea.
with love - M