i did the AeT test to determine the 135 around April last year, then one that determined 151 around June and i kind of just stuck with using 151 as my threshold since then.
Which means since June I’ve been in the very low zone 2 mostly zone 1 range.
Ive been doing a lot of volume, a lot of weeks last year were 180km and one of 200, so i knew i didnt want to push zone 2.
Regarding the nose breathing/ ease of being 5 beats below AeT, i was still breathing from my nose when i did the recent test at 175ish, and could have a little bit of a conversation.
I cant properly compare the recent test with ones in the beginning because the volume of work in-between makes it slanted. And because i am closer to AnT then before it wont seem as easy, but i felt comfortable that i would be able to sustain the effort for 2-3 hours.
There are times when i go out now and do zone one runs and breathing doesn’t feel as easy as it should be. All days are different. I live on the coast and theres is always a really strong headwind that makes it difficult to zen out all the time combined with oppressive heat.
i also smoked for most of my life until 3 years ago, so my lungs have a long way to go.
In response to your last question from what i understand when you do a drift test you will naturally go above your threshold if you want to get close to a 5% drift as possible.
Targeting your perceived threshold at the beginning (after your warmed up), so from there if you did get just below a 5% drift you would of gone slightly over your threshold during the test.
all the best