How often Booking sync calendars?

Hello,

I've set up my website to import calendars from Booking.com every 15 minutes and everything works. But not the other way around: a reservation made on the site almost an hour ago has not yet been updated on Booking.com.

I would like to know how often Booking.com performs the automatic import of calendars and if I can configure this (yes, I know I can do the manual import, but I would like everything to be automated).