Frame cross members

[Erics51chevy]

So as my build is going along smoothly I'm always thinking of the next thing to do all day long. Most of my frame is boxed and want to make sure the frame is as strong as needed. I still have the original cross members in the frame but people have added more to that. My question and thought is how many cross members are too many? To what point does it just add weight?

For a boosted v8 anyway. Also, i have read that the crossmembers are only important between the two axles.

I was thinking an X under the cab and another X under bed.