In a non-communal dining situation at a decent restaurant, I would only tolerate about a minute delay: about the time for the server(s) to walk back to the pass and bring back the missing plate(s). Any decent chef or expediter will wait to send out the plates in parallel. Many restaurants will use heat lamps. Some top restaurants will refuse, and instead refire dishes if they sit too long while waiting for a delinquent cook to finish something.

I guess I usually dine at decent Western restaurants, so I can't remember the last time I've experienced this particular problem.