As someone who was a mechanic in the Army, I feel that checklists more often helped then harmed. Many mechanical problems we saw in the shop were easily attributable to an operator skipping a step on their PMCS. Doing something relatively dangerous or confusing could be error prone, especially for people who haven't done it much, and a checklist can help ensure the safety of everyone in the shop. A good example is running an engine indoors. Before you did it, there were a serious of steps you had to walk through before you turned it on, that reduced people getting sick from carbon monoxide quite a bit.