[kovvy]

I had a protocol fail repeatedly, and expensively, because of a combination of a contaminated reagent and a tiny amount of sample. Took me ages to even approach being able to debug that one as the protocol worked for everyone else. Turned out everyone else using the same materials had so much input sample that the contamination didn't matter, or used the non-contaminated part of the output.

Almost to the day I worked out the issue, I saw an immensely more experienced lab person running an almost identical experiment to my setup. They always added another reagent "in case there's contamination".