I agree with you but level 56 in 4 days just seems seriously too quick, I would have least expected the 80 levels to last somewhat over a longer period i.e. 6 - 9 months on that side of things their doesnt seem to be a sense of achievement.
It's too quick because the people doing this aren't progressing naturally. You find that the early levels pass quickly, that's fine as they're just getting you ready for the rest of the game. The later levels pass slowly if you let them - in any game if you powerthrough, you're going to get there quicker than intended.