I stopped using studs and now only use 1/4-20 stainless socket head cap screws.
This is so I can remove the valve covers with my headers or manifolds on. A long ball end Allen wrench will remove the screws at all angles.

I did the same thing with the intake runner hardware on my ol TPI Camaro. They were originally Torx and it was hard to get a straight shot at a few of them. Allen heads and ball-drivers make intake removal a piece of cake now.

I considered switching to bolts with these valve covers but I really like the way the studs hold the gasket in place and I need things to be as idiot proof as possible.

On mine, the 2 lower bolt holes near the center are impossible to reach with the Power Flow manifolds installed. Makes valve cover removal a real PITA. That's the reason I'm going back together with Loc-tite and lock nuts.