Ive done many stack and whacks and what I find helps alot is to press the fabrics well, then align everything using pins to make sure the print lines up perfectly.......
if using the whole width of the fabric, I cut it along the fold line. Its easier to line up the narrower widths, rather than the whole 44".
Remove pins before cutting........ then keep your 'waste' pieces stacked as well, you may be able to get a second set of blocks out of it, or use 4 layers to do stack n whack 'squared'. Great use of what would be 'waste'.