Best I've been able to handle is 5 seasons, 2008-2012. I don't think I've ever gone longer than that, due to becoming too powerful.
Same here, which is why in my new Franchise I:
1. Chose a team with bad contracts and no cap space, as ample cap space is, in my mind, the key to a quick turn around for any team. I chose the Redskins. They have multiple players that suck, but if you fire them you get something like "save 4million in cap space, pay 20 million in penalties" all the while having maybe 5 million of total cap space.
2. Chose a difficult playbook for the way the game is tuned, that I do not know at all: the Spread Option playbook.
3. Started in the preseason, not the offseason. No picking up McFadden, Rivers, Phillips, Calais, Rice, Johnson, Bennett, and Woodson all in one draft. The Skins drafted almost nobody of note in 2008 (as far as the game is concerned).
4. Force-chose a draft path I do not know at all, Zazalli.
4a. Chose one of the two draft paths that have little in the way of draftable talent, again: Zazalli.
4b. Refuse to use draft potential cheat sheets from the board here.
5. Fired only people who would never, ever, see the field -and- had small contracts. I am still fielding players this time around who normally I would have gutted on day one.
6. No using the 3-day free agent window after the Pro Bowl to either re-sign my own players with expiring contracts, or pick up players who other teams cut after the season.
7. No reloading to re-negotiate lower contracts if they're asking for too much this time or if they refuse my lowball offer. All contract negotiations are done straight up legit.
I am allowing myself only three of my standard "make it easier" strategies, and the first two of those for specific purpose:
1. Exit out of super-sim games before the end if my team is winning. I want a 0-16 or 1-15 record to lock up the #1 overall pick. First I want Zazzali. He's the whole reason I started this franchise with this playbook, and I hear he always goes #1 no matter what. Second I want to see just how bad the salary situation can get and #1 overall will get me there.
2. If I get fired at the end of the season, I'm going to reset until I get the "ok you can stay" message, cause I'll be damned if I'm going to do all of this work and not keep my #1 overall.
3. I -will- do save and reload to scout available coaches after the end of season #1 when I build my coaching staff, because I find it totally unrealistic that any head coach would ever build a coaching staff with the strategy of "hire whoever the first guy that walks into my office and accepts my offer, with only a very vague idea of what they can do". No, he'd look at who is available and what their skill sets are, then see if he can make a deal with the guy he wants.