This page states that you can change your time zone in Outlook Web and that Bookings will then localize your availability times to that time zone (if I understand correctly). However, changing my time zone (either in "Time zones" or "Language and region") in Outlook changes strictly nothing. I would expect that setting my availability to 9 to 5 would mean 9 to 5 in the time zone I am currently in. However, it seems that it invariably refers to 9 to 5 in the time zone of the business, set on the Booking page > Region and time zone settings tab in Bookings...
I understand both ideas, but since I move around a lot it would make sense to have the possibility to choose the time zone to which availability times refer to.
Even for people that do not move around a lot, it still makes sense in the context of distributed teams. In this context, there is a fix which consists in picking some arbitrary time zone for the business, then setting the availability times of staff in that time zone instead of their own time zone, but for people who move around a lot it's just a pain to do this manually every time, not to mention that this prevents a central admin from doing it since he would need to constantly be informed of everyone's trips.
