RE: What you believe is commonly overlooked when tuning or troubleshooting.
I'd say nock fit is definitely one of the most common things overlooked.
Running a close second is tiller. Smart shooters get their tiller properly set and let the poundage fall where it may. They know a bow that's maxed out is not necessarily going to shoot it's best or fastest. They also know a bow that is properly adjusted is going to be easier to tune, will stay in tune better, will be more comfortable to shoot and will give it's very best accuracy.