At first glance, it does seem to have an obvious edge in playing Over 3.5 for the 2H if a game total was set pre-game at 11 instead of 7.
Just keep in mind that the game total is probably based 2/3rds on the starting pitchers. During 2H of a game (6th-9th innings), relievers most likely pitch the majority of the 2H. So you essentially are betting O/U 3.5 2H on whether the combined bullpens give up 4 runs or more for the Over.
I'd think there may be some edges anyway:
1.) a road favorite would mean that if they are winning, the home team would definitely play bottom of the 9th. That's 4 full innings as opposed as 3.5 innings to get Over 3.5 runs to happen (if you are on the Over).
2.) If you have two shaky starters, but both bullpens are at least better than average, then even if game total is 9.5 or 10 or higher, most runs may be scored early and often, but as long as the bullpens are not tired from frequent use in recent games, I'd think Under 3.5 2H would be a better play than playing Over 10.5 in a game total. It sucks when you have to worry whether a game total would reach 11 by the end after getting 8 combined runs in 5 or 6 innings.
* CalvinTy