I'd say the length of a rebuilding project depends upon the league.
Both luck and skill are involved, but in a league with active traders, I think a poor team should be able to bootstrap picks into a competitor in two years.
In some leagues, people prefer to play and trade more conservatively and then I'd buy the 3-4 year figure.
The folks who are most bothered by contraction are probably those who stockpile prospects and don't trade prospects or picks much, but that is a viable strategy, a matter of choice, and understandable.

I only disagree with a categorical statement that it takes 3-4 years because it doesn't always take that long.



Dave N