You want the moon on a stick.
Approximately 25 times a year for 3/4 hours you get 20000 people all trying to use the phone network. The mobile companies aren't going to pay for more bandwidth or stick another cellsite in for 100 hours a year.
Bad as in poor signal (inside a steel and concrete bowl) or bad as in difficult to use mobile data in close proximity to thousands of others trying to do the same ?