I dont get why you people are a scared of rebels... Do you never ally anyone? Give an ally military access, and they will clear them for you, if you cant.
The whole point of taking land is to increase your power, But if you let autonomy sit at 50% you have to take twice as much land than if you just decreased autonomy and killed a rebel stack.
By the way, after rebels pop, all the revolt risk goes away (HURRAY!). So again, give Bohemia access, and he'll gladly waste his man power for you... thus being less likely to drag you into a war you dont want.
Edit add; I have had games with no allies, and no manpower, where I was slow to reduce autonomy. Like my Aachen to india game... Nobody wanted to be my friend... Being catholic in india in 1450 will do that.
I don't see the use of lowering autonomy in 1BT fish while allowing it to spawn a rebelion in 5 other provinces. It's a bit too gamey to me, too.
Really, when I'm small, I usually don't increase autonomy because I can't afford it (I sometimes increase it a couple years after conquest when it's close to a revolt; sometimes I don't have to and when I have to, I still benefit of a few years without increased autonomy). I also try to decrease it in key provinces, ie I conquer 3 provinces with the same rebel type, one being say 10 BT, and the other two 3 BT, then I increase autonomy in 3 BT (no unrest), while decrease in 10 BT (some unrest, but parking military there and waiting is usually enough to keep it very low; might have to do the occasional harsh treat though).
Once I'm a big enough blob, I just increase on conquest; this just allows revoltless blobbing almost regardless of the pace of expansion (and I'm too rich/strong to care about what I get from new provinces anyway).