Chairs are not equal. One barber may take twice the money of the next through speed, service mix or simply being asked for, and knowing that per chair is what informs rotas, pricing and who to keep happy.
Mixing walk-ins with bookings needs a rule. Holding slots for people who turn up keeps the shop busy in quiet hours, and holding too many means booked customers wait, so the ratio has to be decided rather than improvised.
The customer list belongs to the shop only if it exists. When a barber moves on, the regulars go with them unless the shop knows who they are and can invite them back, and most shops discover this the week it happens.
The money runs two ways. A chair rented to a self-employed barber and a barber on wages produce completely different accounting, and shops running both need to keep them cleanly apart.