Limited approach defense is something that can and should be applied in a variety of assaults. The basic principle is to use mobility against your opponent and allow only a limited number of enemies to approach at once.
A small scale example would be a lone defender with a drywall hatchet at the top of the ladder of a Billboard killing zone zombie at a time as they reach the top. By engaging only one enemy at a time, you change the fight against zombies to a fight against fatigue.
This principle can and should be applied in every confrontation. On a larger scale against zombies, a box canyon or an alleyway could be used. Care should always be taken to ensure that there are no more hostile forces than can be effectively coped with.
You should consider what you are going to do with the zombies you kill. Will leaving them in place assist you ie blocking more zombies or will it inhibit you? If it is the later you will need to consider how you will clear the bodies.
The number of zombies you might receive through the limited approach is likely to vary but generally this tactic is used in a situation where you will be outnumbered so you might want to consider working in teams. One responsible for killing and the other responsible for clearing\disposing of bodies. This approach will also allow you to switch jobs and may provide opportunity for rest breaks.
A limited approach may be associated with entry\exit points of your base but need not be. A limited approach defense structure may be constructed anywhere with the intent of luring and killing zombies.
The most important thing to remember with the limited defense tactic is to understand at what point you make a final retreat or close\seal\barricade the bottle neck when things are getting too risky. This is assuming that you have planned to deploy this tactic beforehand. However this tactic may be used in a last ditch defense of a location or as part of a planned retreat.