There are limits to timeouts. Coaches are only allowed to make 3 visits to the mound during a regulation game. More than one in an inning to the same pitcher requires a pitching change and each visit after the aloted 3 requires a pitching change. So if a team has unlimited pitching, I guess you could say there is an unlimited number of time outs. But I am not aware of any team that has unlimited pitching.
Other than this, it is the umpires discretion as whether a time out is granted or not. Players can only "request" time.