It depends on the size of your school. Where I played we were 4A which was the highest level in SC. Everyone works both ways, although everyone didn't play both ways. Our depth was the ability to play both ways (ex: I played SS but would have backed up any WRs who got hurt and vice versa there was a WR who backed me up at SS) there were a few who straight up played both ways.
EDIT: I will also say that a majority of the schools below 4A have most of their players playing both ways. So in other words it is more common than not to have kids playing both ways in SC.