I do one top at a time, but have a lot of tops stored in boxes that have to be sandwiched & quilted, plus I've been hand quilting 2 king sized quilts for years. However, those are not a problem for me ... my problem is the need for perfection. All my seams, points, etc. must be perfect. I can live with something being 1 thread-width off, but any more than that, I have to re-do. The point being is that I un-sew a LOT and spend much time making corrections. This is particularly annoying when I've almost completed a quilt top and am down to the big stuff like putting rows together and attaching borders. Although I am pleased with the final result, I am truly sick of it by the time I get done.