using rebel lands as buffer zones

Ouch Alexios, re-emergence can hurt worse than rebels, especially like that.

I have been playing the Russians in High. The Provence just to the West of Lithuania on the Coast (either Pomeriania or Prussia, I know it starts with a P) has some grumpy rebels. I watched Poland take the Provence, and a few years later the Provence rebelled. I don't know what the Rebel army was made of, but there were 2 stacks of them. Poland withdrew from the Provence, and the next year one of the stacks moved to the Provence just to the South.

The Polish eventually cleared up the mess only to have the 'P' Provence rebel again later. The Poles haven't been back since.

Re-emergences can be helpful, just depends on who they attack when they come back.

Sometimes of course you can use enemies as a buffer zone. The Argonese keep refusing cease fire offers, yet they 'nicely' keep their allies the Spanish from attacking me by buffering me with the three provinces they hold. Love those buffer zones, busy attempting to create some more in the HRE empire after the Germans decided to attack me (after dropping me as an ally on the flimsy excuse that I attacked the Italian navy who I have offered countless cease fires too, all rejected). Now as I invade, and raze I am leaving behind unhappy rebels who fight the Germans and deplete their troops even more.