Building and growing men's haircut business may not be any more complicated than knowing how to manage walk-in traffic.
Barbershop culture is built around the walk-in. The vast majority of new guy haircut opportunities in most salons in America are walk-ins.
Walk-ins have expectations of service timing. If you say you take walk-ins it is not enough to be willing to take walk-ins; you need to be able to have them in a chair and engaged in a service in less than 10 minutes. That is the time limit. If you cannot take them immediately it would better to quote the wait as ten minutes and seat them in five. Under promise and over deliver. That is not to say that you can tell them thirty minutes and service them in fifteen. Thirty minutes in NOT a walk-in. Thirty minutes from right now is an appointment.
Take a page from the chains. Some of the chains take appointments. Some now offer call ahead service in which you can call and be placed in the queue for cutting. You move up as time progresses and when you walk in your wait has been shortened. Some chains place the call-in at the front of the queue so when you arrive you are "next up." Guys love "next up." You just need to be sure this service is fully explained in print or on the wall so fisticuffs do not break out when a guy walks in and sits right down while other waiters keep waiting.
The chains also know that the difference between servicing clients immediately and running a wait bordering on unacceptable is sometimes no more than one extra cutter on the floor. The cost vs. return ratio on this can be huge for a salon looking to grow men's hair traffic and loyalty.