I usually have 2 (or more projects) in the “works” at the same time. Generally, one I am building, the king size quilt, and one to stitch and quilt at the same time (see photo).
When machine quilting - it is good to set a timer for about 30 to 40 minutes, then get up and move around, blink your eyes and focus in the distance for awhile. I am seated when at the machine and mostly stand or sit on a tall stool when building a quilt. It’s nice to go back and forth between projects - or like today, get other chores done when the timer rings. Have a good day!