I rarely make mistakes - but I've had 2 happen in my 2 years of designing in here. I had one board that underwent a late parts move; 4 wires ripped up to make room and never re-connected, another with 1 letter missing from name - so 2 pins ended up with +5 instead of +5V.
A 2nd board I converted from DIP to TQFP - 1 output signal attached to the new symbol got connected to A6 instead, which is analog input only.
Both easy to get working with wires added where traces were missing.
Everything I've offered up to the group for purchase has been error free.