For whatever it's worth, I didn't start running sweeps effectively until last season. I finally had a fast enough RB to make the corner, and built a strong o-line to block well. Prior to last season, I was more of a passing team or strictly inside runs since I would usually take a loss on an outside run.
It does make a difference based on your team's personnel. Teams with fast LBs can still stop or slow down my running game and get to the corner in time. I think it is all about playing to your team's strengths. I run more now, but if I didn't have a good RB I wouldn't call those plays and go back to higher passing or inside runs. Also, if you look at my last two game logs, my longest run plays were both inside runs, not sweeps.