Generall I cleco every other hole for final drilling. You can't always keep a regular pattern going, and so it's easy to lose track when you move cleco's over to drill the next set of holes. So I put a Sharpie mark at each cleco. I then drill the holes without the clecos. When I move the clecos over to the drilled holes, I now know that any hole with a Sharpie mark needs to be drilled.
