It happens quite often in long LaTeX files that LaTeX "tries" to fill a page, but because of various priority rules to theorem environments for example very much white space and large line spacing is produced. It's hard for me to produce a minimal example for this, but I think you have all seen this. Here is a screenshot of an example:
Of course this is very unpleasant. Usually I try to get rid of the problem with ad-hoc solutions, for example expanding some paragraph etc. This costs a lot of time, especially in long texts, and after a small layout change one might start over again. How to prevent this automatically? Or at least, how to let LaTeX send warnings to the compiler each time too much white space (which we would have to define first?) is produced? Or, how do you deal with this sort of problem?