I tried to go through my team history to see if I've ever had an undefeated season. Maybe the first time I promoted out of D.IV. But the servers kept giving me errors trying to check. I've gotten some lucky breaks to get this far, I doubt I'll make it all the way. But I certainly plan on promoting one way or another!
Someone did a study one time, maybe Wozzvt or one of the other USA Offsite statheads, where they collected average enthusiasm at gametime broken down by division. It looked something like
I: 11.8
II: 11.2
III: 9.5
IV: 6.3
V: 5
Back then, effort and gameshape management was probably the most challenging aspect of this game. I'd say it's still important, but squeezing value out of 33+ year olds is a lot bigger deal nowadays...