I also have very little tolerance. But I have learned that using sashing between blocks--and marking the 'expected' points on the sashing-can make a huge difference. It's such a persnicketty thing, but marking where the blocks should start and end often means stretching just that 1/8 inch or easing in that 1/4 inch per block and ends up making the whole project less stressful.
I do not participate in swaps. Heck, I don't have time to finish my own stuff much less work to someone else's time table. Right now I have a Winnie the Pooh baby quilt half completed on my table, ideas for a doggie blanket for a co-worker in my head and have just ordered the fabric for my DGD's big girl quilt--design in limbo but percolating!!