This functionality is relevant if shops want to give their customers more start time alternatives than the clock hours in the online shop. The functionality doesn't affect the check-in kiosk or rentals made through the admin view because of the start times of these rentals are dependent on customers' arrival and physical presence at the shop.
Start time intervals and availability limitations can be handled in the Product's settings page.
Once you have navigated to the product's settings page that you want to edit, under the Online shop settings section, one can define intervals for start times. In the image above, for example, the shop has defined 15-minute intervals for start times. This means that in addition to clock hours, customers can choose to start their rental at quarter past, half past, and a quarter to the clock hour.
To avoid the shop getting too crowded during specific start times (e.g. in the morning when the shop opens), the shop can limit the number of orders it accepts per start time based on the number of customers employees are able to serve in the selected time period. This helps you to manage the traffic and avoid excessive crowds in the shop at the same time.