I've hit the wall before, and one thing that helps is to stop when I feel not into it and get some chores done around the house that have been put off. Sometimes I'll make a list and say when that list is done, I'll consider restarting the plane and very often when the list is done, I'm emotionally ready to get back at the plane.

Another think that makes a difference for me when I hit the wall is to stop construction and clean up and put tools away so that they don't have to be hunted.

I've never allowed myself multiple build projects. What I do allow is getting a plane when it is available and laying it back until it can find its way to the focal point.