No doubt they would say stuff like that. The increased crosses are to try to overcome the major tension loss you will get from not prestretching.
Bet you its not AP specific. They will give that rec on any frame that size.
There was a similiar post in the esp thread with a similar rec from Ashaway. There was a rep here and Iirc he was part of the ESP thread. Never recall him saying not to do the rec 60/40. His handle was julianashaway if they still have his posts you can see.
Fwiw I used to work for a major electronics company. This was when HD was coming on the market and they didnt have an HDMI connection. If you called their tech support and asked them if you could use an adapter from HDMI to Component vid they emphaticatically would say NO. That puzzled me a ton because in the field we were regularly using such adapters with no issues. When I talked to the head of tech support he acknowledged that adapters would work but because they hadnt tested all of them on the market or even one, they couldnt support such an adapter for customers... even though many of the adapters workd great. By test I mean a rigorous engineering test with several popular TVs and different adapters.
You cant see hiw a manufacturer would discourage something they never tried??
Also the whole stringing industry is way behind the times and IMHO doesnt even understand the frame distortion one gets with nat gut/ poly ( which they string all the time). So Ashaway would have an uphill battle trying to change a ton of minds and well stringers are the most opinionated people on the planet
And truthfully zx is pretty fragile if you dont know how to use it. Bet they are afraid of all the “it broke while stringing” compalaints and are recommending no prestretch because they dont know how it will be done, etc. Said another way, what they wrote doesnt mean 60/40 or 60/30 wont work. Have you read the ESP thread? 22 pages plenty of people doing prestretching and differentials. It even explains the differential and what the stiffness of kevlar means in relation to the stiffness of zx and how the kev mains will lose tension more iirc.
https://tt.tennis-warehouse.com/ind...-can-see-the-future-of-tennis-strings.468680/
Did they tell you how to string it?? Bet not
Here in case I am wrong. It wasnt me but one poster claimed that this vid came right out of the ESP thread: