I have yet to keep any the 7 quilts I've made. They've all gone to family or friends. I have several yards of fabric picked out/folded on bolts and set aside for specific quilts TBD. Does that mean they are UFO's? I've also participated in several I-Spy 5" block swaps. I have 200-300 blocks ready to be pieced into 2-3 quilts but haven't chosen the layouts yet. Probably a disappearing 4 patch, tumbling charms or tumbling blocks patterns.
I will only work on one quilt at a time. That gives me the motivation to finish before I start on another one.
I can't imagine having 150 quilts completed and another 50 UFOs! That's a serious addiction!
Best of luck with whatever you decide to do.