I want to allow volunteers to sign up for pre-determined shifts of varying lengths. Is Appointments+

We are a public radio station and we have phone answering shifts.
We would like to allow volunteers to sign up for those shifts on our site. The shifts vary in length throughout the day and the number of capacity varies as well.

Example. Weekdays we have five different shifts.
2 available spots for 6am-9am
6 available spots for 7am-9am
2 available spots for 9am-12pm
4 available spots for 12pm-4pm
8 available spots from 4pm-6:30pm

Is Appointments+ right for this?