Hi Joe,
Thanks for checking out our plugins!
You should be able to do this with The Events Calendar and Event Tickets (free RSVPs) or Event Tickets Plus (paid tickets). You can create 15 minute events at whatever interval you need (overlapping times is not an issue), and then add tickets to those events. Event Tickets Plus will also let you do things like collect additional information from attendees at registration.
If you are looking to segment a single event into slots that people can register for, really the only way to do that would be to create the event and then set up multiple tickets for each slot. For example, if you had a 1 hr event starting at 8am, you could add different tickets titled “8-8:15 am”, “8:15-8:30 am”, etc., and set a maximum number of available tickets for each “slot”.
Our refund policy does offer a full refund within 30 days of purchase if you’re not satisfied, so feel free to try everything out and see if it will work for you!
Please let me know if you have any other questions!
Thanks,
Jennifer