Pretty Sure I'm Right

[Chess Ref]

Coach of Defensive team wants a time out. Granted. 3 Batters later, same inning asks for another time out. I grant it. My partner says at that point he needed to change pitchers cause it was the 2nd conference in the same inning. I disagreed. So we moved on.
I come home and go through the rulebook and can't find anything that limits the number of conferences per inning.

Am I missing something or is it possible my partners baseball umpiring experience is leaking through ?