When I used to teach, I used to teach simply using 1 min for the entry as well o0n a 4NM GPS Hold but, like USMC, I believe the texts show more support for the 4NM entry leg, regardless of entry type (TD or P).

It seems kind of over-kill in my mind to fly OB for 4NM on a teardrop entry but the only thing that is 100% definitive in the AIM about this topic is as long as you remain within the 4NM barrier, you will be protected. I suppose the FAA and NACO design the hold procedures to account for this 4NM TD entry type.

Maybe the AIM's procedure not to exceed 200 KIAS during a procedure turn (and a hold in lieu of a PT I would assume as well) helps to keep you from straying to far away from the Inbound Course when doing a teardrop entry.

Clear as mud lol