You want to measure to the opposite wall as well, then you adjust the rows to your liking, like making it say 3/8" out of parallel on each wall rather than 3/4" on one wall. Also, which way it runs affects your fudging too, usually you want lines perpendicular to windows, so if you enter a door any misalignment with the adjacent parallel wall might stand out. It's a judgment call on where to fudge or which wall to use as an anchor.
Don't forget to calculate the first and last parallel-to-wall rows so you are not left with a 1/2" wide plank, the manuf should have a minimum width of plank (at least for floating).