I think in 1 long realm you can achieve to have nobody in your 3X
But one thing I notice in 4 months realm, when I finish research 10 provinces, meds 17 and beureaucracy and military research and I am ready to fight, the realm closes, farm 4 months or even 5 months, 3 months of killing is quite good and make everyone beg for your mercy, muahahaha.
but seriously 8 months realm is too long.
I prefer 2 research ques and building ques and 4 months realm stretch to 5 months with normal provinces price. So when I finish farming, I can start to kill.