Sometimes I work on one project for a few days straight till its done, especially if I have a deadline, but I've become quite fond of working on a bunch of things at once. It keeps me from getting burnt out on one thing and sometimes I find I can get more things done that way. Like I can't sew while I'm watching tv because the sewing machine's too loud so while I'm watching tv I'll knit or something like that, and then after my show's over I'll switch to my sewing project and then before bed I do a little embroidery cuz my bedroom's got the best lighting.....and yes, I'm one of those people that can't sit still and always has to be doing something with my hands
But if you do start working on multiple projects at once I'd suggest making some sort of "work in progress" organizational system. Personally what I did was get some cheap clear vinyl and make little simple pouches, you know just like cut a rectangle, fold it in half with a little at the top for a flap and sew up the sides. then each project plus supplies goes into a pouch and I hang the pouches on skirt hangers (ya know the hangers with the clippys at the bottom) and then the hangers can just get hung in the closet or on my wall (well on a peg on the wall) so it saves space too. I hope that made sense/helps.