Realm Divide triggers

[Leptomeninges]

Anecdotal:

In a previous H/H/L game RD triggered with my 19th province (I was able to get 18 without triggering it.) No vassals.

In my current VH/VH/L game RD is going to trigger with my 18th province (I am only able to get 17 without triggering it.) No vassals. I can also see the bar move with some heroic victories which I could not in my previous game.

The impact of victories wasn't too appreciable in my previous game and I was wondering if they really filled the bar. For myself, I'm convinced that they do. In fairness, I've been in war far more in my VH game, but given that I can visibly see the bar move, it's also possible that the bar is effectively shorter as difficulty increases (even if it isn't visibly shorter).