In OOTP, a player with option year used can be sent back and forth without limitations between majors and minors. Players could send down exhausted relievers then call them back 2 days later.
According to MLB
rules:
Upon being optioned to the Minor Leagues, a position player must remain there for a minimum of 10 days before he is eligible to be recalled to the Major League roster. For pitchers, the minimum is 15 days.
I'm using this as a house rule but I don't understand why it's not implemented in game. It doesn't sound very complicated.