You'd be surprised. A cork 5 is a pretty easy/natural rotation to spin. Some people say it's easier than 3s. I've done some practice attempts in to foam pits/on tramps with no board and it is a pretty fluid rotation that made me think "Wow, this is really a within reason trick for me to do". Lock those 3's first, and I think cork 5s will flow pretty naturally.
Well I've got my back 3's on lock off 25's, front 3's off 15's are finally feeling good, been focusing on them for 3 weeks and plan to take them to the 25 and don't forsee any issue. I'm getting bored of 3's and the rotation is effortless so I guess its time.
Thx for the input - maybe I'll be able to cork one out yet. I'll be studying this video more this week prepping myself. The 3's are almost too much muscle memory now so I'm gonna have to focus on keeping it going.