Why do you need a Volume Scheduler?
There are many reasons.

First, it's extremely annoying when your phone rings during a meeting, a business conference, or any other sensitive occasion. You can put your phone on silent, but you sometimes forget to do so.

Second, even if your phone is on silent, you might forget to reactivate the ringtone when an important call comes in.

Third, imagine you're in a crowded place and your phone keeps ringing in your pocket, making it impossible to hear the ring