what's wrong with doing whatever you like when you're playing a game in 1-player mode all by yourself? it's not like developing the patience to grind out one and a half seasons of my player mode is going to save somebody's marriage.
if anything, the time spent screwing around on your xbox (if there's more important stuff you should be doing) is gonna be a larger detriment than anything gained from the experience.
I don't mean to be overly critical here, but it seems a little misguided to unload a pile of Larry Brown style "play the right way" on some guy in this particular context.
To answer the OP's question: I have no idea. It generally takes me about a season and a half to get enough skill points on the XBox version to get a legit 99 overall dude. Honestly, I tend to get pretty much unstoppable before I actually hit 99, so eventually it gets to be a matter of "what skills haven't I maxed out yet?"
The only thing I can think of is just the basic strategy of using your drills to get the most expensive stuff, but that's just economizing, you know?
EDIT: Nevermind. The OP posted this literally YEARS ago.