Funny...I've been thinking of that word a lot lately. "Patience" and "tolerance," go hand in hand, but they mean different things in the sewing world.
I think that my quilting tolerance has become smaller over the years, as I've become a better quilter. Still, I'm far from perfect, so for making blocks, I would say that they should be within 1/4" to 1/8" of each other. I don't like to stretch seams too much and so, I find myself re-doing seams, instead of stretching, in order to make things go together better. Also, I'd rather have all blocks off by an 1/8" and create a slightly, small quilt, than to try the almost, impossible task of making them the correct size.