Many cars I've raced would not cut a quick enough reaction time. Over the years I've learned to "bump" them in. Seldom have I had a car that needed to go all the way deep(top bulb out).
I've found one bump is usually worth about .030 in R/T. For instance at the Norwalk Chrysler Classic I made 4 passes shallow staged. All between .060-.068 R/T. Not good enough to go very far in eliminations. Bumping in the next 9 out of 10 passes were .004-.030. As you can see it is not as accurate as your bump in distance will very. It also will slow your E.T. by a similar amount. Still it works better than being slow. It just takes practice. There is aprox 4 bumps to turn the top bulb off in my case.
Doug