I work on as many as I feel like. I still work full time, so if I see something and want to try it, I go for it. If it ends up resulting in a finished top that goes in my "to be quilted" pile, that is fine and if not, that is OK too. I have a LA, and quilt when I feel like it, but if i have over 200 tops ready to be quilted when I retire in five years, I'm OK with that.
I rarely make quilts for a specific reason or recipient, so I rarely have any type of deadline. When a quilt is finished, I find it a home at that time.
There was a time I was getting rather compulsive about my hobbies, and feeling pressure to work on things just to get them done. It started not being that fun so now I give myself permission to do this simply because I enjoy it.
I am actively working on 4 samplers (I do 10 blocks and then switch to the next one) and decided to join the Dresden Plate party, and am nearing the end of the Row Robbin swap. I like to have one machine embroidery quilt project going while piecing, and am getting one wrapped up so could start another. Just assembled a lap size quilt this AM and deciding if I want to call it done or add a border. I've got three tops that need something "fixed" before quilting, and at least 10 waiting to be quilted. And at least two that are quilted and need binding.
I know I've got at least 4 sets of swap blocks I've not assembled, and 4/5 totes of fabric and patterns I've not done anything with, and 4 kits I purchased that I've not started.
I really have no idea how many "started and abandoned" quilt projects I have on hand. I decided to move those totes to the shelf above the cutting table so I'd remember them. Then I need to decide if I want to start working on them again, or send them on their way. I finish most of what I start, so I'm not going to stress over the few that no longer give me enjoyment to work on.