In Franchise Mode, start a game, and fast forward to either inning 7,8, or 9. After that, take over your team, and look and your pitcher's stamina by pressing select. It should be completely full, even though they have thrown 100 pitches or so. If you don't throw too many more pitches with them in the game, then their stamina should stay full for the next game, meaning you could pitch every game with the same starter.