This page assumes one architect. You are the practice, the diary is yours, and the thing being protected is the day you draw in. Three others cover what happens when that stops being true, and they divide by what is being booked rather than by how big the office is.
When it is people, and there are several of them, go to client booking for an architecture practice. Five architects means five sets of site days, and the hard part is that a client wants the one who is actually on their project rather than the first free hour in the building.
When the person being booked works for the council and the second audience is a village hall, read planning consultation booking software. A pre-application meeting and a public consultation evening are not the same kind of thing at all: one is an hour that has to suit three diaries, the other is forty chairs and a number that has to stop.
And when the argument on a Tuesday is about the crit room rather than about anybody’s time, room and equipment booking for a studio is the page. The plotter, the model shop and the good meeting room behave like bookable objects with their own hours, which is a different job from booking the people who want them.