Quite a few of my crews have 3 skills, and I think I'm up to 5 crews that have 4 skills (T34, IS-3/6 268, vk3601, and E-100 minus that damn 2nd loader). Most of my 4 skilled crews are probably in the 60-70% range on thier 4th skill, while I do believe my best crew (T-34) is sitting close to 90%. I would have to be home to count the number of crews I have sitting on thier 3rd skill, but its at least another 5+ crews.
Its that last 5-10% that take a damn eternity. The only reason I have such good crew skills is due to all those x2/3 crew xp weakends, its the only time you can see any appreciable improvement in skill %. They also had like 2 weeks of crew xp bonuses last christmas/new years and I happened to be off and enjoying a staycation, of which I played the shit out of WoT.
All tier 10s are on discount this weekend, now I just have to make the decision to buy the 50m or just stick with the E50. I have the garage slots for both, which isn't the concern, the two main concerns are: 1. which one gets the good crew, and 2. Is the E50m any fun to play, or funner to play than the E50.