Outlook Start / End Times Don't Match Actual Calendar

I've had a couple of users recently whose Start / End times and Work Week have been set

Start 8am End 5pm M T W Th F.  But their calendar or any shared calendars show start times as 11am to 8pm a 3 hour shift.  What are we missing that would cause this simple setting to be off and not match what is shown for start and end times?