Just remember that guarding a passage is guarding a passage, and blocking is blocking – don't mix them up.
Also, I doubt I'll be calculating the number of monks using a formula in reality. It's been known for a while that there are 20 of them, not 30 – it's been verified in practice. Once, there were 23, I think, with an upgraded one, which already surprised me. Or maybe the upgraded stack adds to the number, or it's an exception. The same goes for other guards I often encounter – pegasi, wood nymphs, crocodiles, archers, golems – you roughly know the number when you attack. Play more often :)
But in general, I repeat, kudos. Good job.