I don't think the formula really tells us a whole lot about how tough one's schedule is. It doesn't take into account a team with a winning record against weak teams. We have a relatively tough schedule(unlike most Pee Dee teams) but we also have a couple teams with winning records that don't play real tough schedules.
To qualify my statement about most Pee Dee teams, here are the teams we played this year and their ranking within their division, or their current status in their region.

North Myrtle Beach #9 3A
Waccamaw #2 2A
Thomas Sumter #6 SCISA
South Florence 1st in their region, also 4A (played 3X)
Wilson #15 3A (played 2X)
Governor's School #4 1A (played 2X)
Our other two losses are to West Florence in the first game of the season and Hartsville on PK's, a game we were winning with less than 8 to go.

Last year people made the statement that we didn't play anybody, so I went and made what I thought would be a tough non-region schedule. No offense to my region foes, but we aren't where I would like to be in respect to the rest of the state.

I also agree that the rankings don't really matter in the end anyway. That comes from someone who has watched his #1 Buckeyes lose the National Championship two years in a row.