At least in RI, junior varsity football games would always be on Monday or Tuesday after the varsity games. I was told that it was mostly a hedge against injuries, since most varsity teams would dress pretty much all their JV players except the meekest freshmen. (i.e. If a couple of your varsity linemen go down, then you might want to use a JV kid, but for player safety you don't want him gassed from playing his JV game earlier that night or on a Wednesday or Thursday.) I have no clue when JV even plays in Texas, because between the roster size for varsity football, the bands, the cheer squads and so on, they were actually offering less sports than I was used to in Rhode Island.