To conduct great matters and never commit a fault is above the force of human nature.

Anyone handling anything large will get things wrong, and no degree of care removes that. The scale of the work and the sheer number of decisions guarantee some bad ones, so demanding a clean record is really demanding that nothing significant be attempted. Errors are part of the cost of doing the thing at all.

Budget for mistakes rather than being shocked by them, in yourself and in the people you rely on. Build in a way to catch them early and a habit of saying so plainly. Then judge the work by the pattern rather than by its worst day.