I have 1-2 quilts going at a time typically. I work on the hand applique until it's all done, then I start piecing & FMQ. At that point, I start my next hand applique project so I always have one thing that's portable at all times.
The main thing I found that was throwing me off was going to live project classes because I'd start a quilt there even though I already had 1-2 going & then wouldn't have time to work on it. Next thing you'd know, another interesting project class would come up & I'd join it, too. Trouble, trouble, trouble. So instead, I started looking for opportunities to just sit & quilt. My LQS'es have UFO groups -- some with an "instructor" who provides feedback upon request and sometimes will do a short 5-minute technique lesson, but not anything that has to be used for a specific project. When possible, I also try to go to my guild's Saturday Sew-In's. And today, I'm hoping to get over to LQS because when you buy your fabric there, they let you come & use their classroom space & Bernina machines any time there isn't a class in session. It's a solid block of time when I can just sit with other quilters and focus on making progress on a particular quilt. I make sure only to bring about $20 for emergency supplies -- not enough to go shopping for an entirely new quilt project.
I would encourage you to think about the circumstances under which you tend to start new projects (classes, fabric shopping, guild events, etc) and then try to limit your access to that as much as possible, and instead fill in with extra time working on your PIGS with other quilters. Quiltmaking is always more fun with friends.
