This is got to be one of the most common triggers everyone is going to be doing; bathroom timers for the light that gets left on. Here is an example on how to setup a bathroom timer.

 

My personal suggestion on length of time is 1 hour. I have found that anything less just gets bothersome especially when the ladies can end up being in the bathroom for quite a long time.

 

In this code you can see there is more than one button in the bathroom so in order to make the timer work for both buttons they both have to be checked.

 

If
       Status  'Guest Bath Main' is not Off
    Or Status  'Guest Bath Tub' is not Off

Then
       Wait  1 hour 
       Set  Scene 'Guest Bath Scene' Off

This works well too with control condition so if you want it NOT to work when other scenes control the bathroom lights then use control instead.

Basically, you are setting the timer to stay on for an hour once it detects motion. I totally agree that this would be beneficial during certain times of the day, i.e. morning. However, what about a late night bathroom trip, which I wouldn't think you would want it to run for an hour. However, have you thought about changing the function to maybe 7 minutes during the most common sleep times for you and your family?