This is a great question with a not very great answer. Training intensity zones are already a somewhat artificial construct. The less tied they are to your personal metabolic response to exercise, the more artificial, arbitrary or disconnected from reality they are. The percentage of some HR value, especially maxHR and even more especially if that maxHR is determined by an age related formula is the most arbitrary and thus suspect method of setting zones. We debated long and hard before including it our book. I won’t get into the thought process here.
Being able to anchor the zones to some actual metabolic events in your physiology is the first step in making the zone system meaningful to you personally.
WARNING: Keep in mind that the HRs at which these events occur are not fixed and will vary form day to day depending on your recovery status/level of fatigue as well as fitness. So trying to define these zones down to a beat or two of HR is false precision.
Having 2 anchor points, AeT and AnT gives you the top of Zone 2 and the top of Zone 3 in a convention 4 or 5 zone system. The difference between aerobic zones (1 and 2) is a bot arbitrary and not easy to define. The distinction depends a great deal on the aerobic fitness of the individual. A safe rule of thumb for setting Z1 limit is 15% below Z2 upper limit.
The upper intensity zone 4 is going to be set by an intensity you can maintain for 5-8 minutes at the most. This is hard training that is why it is done in interval style. If you use Z5 then this is as hard as you can go for about 1-2 minutes.
I hope this helps,