Can I control the ringer volume based on a timer/clock? My wife leads a very scheduled life.  She has a meeting every morning from 6 to 8 am and does not want it interrupted by phone rings or text boops, so she sets the phone to silent.  And never turns it back.  So it is nearly impossible to call her.  

Simple solution, use clock to turn to silent and back to active.  Nope, doesn't do that.  Must be an app for that!  Nope.  A few apps claim so but actually just set timers to remind you to turn it back on and, since it is in silent mode, they just flash the screen.  Which does little good in a purse.

How can we accomplish this either with built-in functionality or with an app?
Apple does not allow apps to "play with" that system setting. That's the technical reason why there's no app for it. It might be able using a jailbreak tweak if it has to change every day (for example: monday between 2 and 4, tuesday between 2 and 3 etc.)

However if you go to:


Settings
Do not disturb
Scheduled
Pick the time of your desire
You're done