In fact South Carolina teams are at a disadvantage when preparing for regionals as most states hold their state championship in the spring as opposed to the fall. Thus a state champion from Ga (for example) has just completed many high level challenging games within a month of regionals.
Fitness wise, game fitness and game speed are to their advantage unless you find a way to maintain your level. Coaches have to do this for the benefit of the team.
At the same time you would hope there would not be many conflicts when it comes to weekends. Most HS do not play on weekends