Set A Unique Duration for Appointments+ & Make Appointments Page Reflect That

This is in regards to my appointments page:

1) I adjusted the function (time base) code to include 50 mins, but I think I'm missing a step because I got an error on the Appts Settings Page. See screenshots attached.

2) I need the appointment durations to reflect 50 minute sessions starting at the 10th minute of each hour.

For example:
6:10AM – 7:00AM
7:10AM – 8:00AM
8:10AM – 9:00AM
9:10AM – 10:00AM

What code or settings would I need to adjust to do this?