az_prof
Footballguy
I've never felt the need because I am sort of always monitoring the age and talent of my team. That isn't to say that I haven't had some bad years but just doing the normal drafting process I've been able to be a strong team in two years without "blowing it up." If I took over a team that was pretty much devoid of talent except one or two good veterans I would probably try to trade those guys for as many picks as I could but in general if you have to turn over 50% or more of your roster then you are doing something wrong.