This is what we are talking about with formation exploit: formation capture exploit.mp4 And this: formation gathering exploit.mp4   The problem with this approach is that, if you need to garrison, say, around 40 units to prevent your building from being captured, out of an average of 150 soldier units you might have in a 200 pop game, you end up dedicating 26% of your units just to guarding a single building. It makes more sense to increase capture resistance.

I agree with that. The issue of too many units capturing one building in the first place.

This was already the case, adding regen rate just shifts the curve rightward. Also, I don't get how adding 1000 points would help that much in the cases you bring up. 5 seconds to maybe 5.5 or 6 seconds?

That’s a nice move. 35 and 50 with an upgrade sounds good.    I’m not exactly sure which issue you’re referring to, but in any case, 20 is a low number. Increasing it would make sense.    Let’s say it’s better not to stack all your hopes behind one fortress. 

That would be one of the easier balance corrections, but it wouldn't fix the issue.  What if a player attacks you with 200 Marian Roman Legionaries? That are magically stacked in a corner of your Fortress. The end result would be the same. No, the enemy needs to surround the Fortress, and you can't surround it with 200 units.