The square cut inaccurately asks neighboring pieces to absorb the difference.

An error at one edge does not stay at that edge. Every piece joined to it has to be eased, stretched or trimmed to hide the gap, so a few careless millimetres turn into extra work spread across everything nearby. The person who cut it may never see the trouble, because the trouble belongs to whoever assembles.

Measure once more on the part that everything else attaches to. If you are the one absorbing somebody’s differences, say so early and specifically rather than quietly compensating for the whole run. Silent correction teaches the cutter that the cut was fine.