What logic does BI Use in determining whether to break to a new page?

I have used this forum in the past, and I have really appreciated the support that I have received from it.  I do not have a tremendous amount of experience with BI, and one rather "intractable" problem that constantly frustrates me is that I simply cannot understand the logic behind page overflow in BI and it is really frustrating because, as a developer I am accustomed to being able to debug code, and I do not have that option here (if there IS in fact a way to debug BI applications, that would be really good to know!).  My application