One strategy that may help is to have two pages in your diagram, where one includes more detail. I don't do it often, but when needed I will create the more detailed version first, then duplicate it and reduce the detail by just deleting boxes and maybe rerouting some sticks. You end up with more whitespace but this can be used for a nice "enhance!" effect when flipping between pages. This can however end up with an unreadable version of the high level diagram, and it may need to be reorganized. And of course there is more effort in maintaining multiple versions, if maintenance is required.