My post may seem not to answer the question - we were posting at the same time.
If you are having fitting split after a while due to stress on the fitting due to PTFE tape, I would find another type of fitting.
I would put that down to the quality of the plastic in the fitting not the jointing method
We do keep crossing posts but all useful stuff!
Yes I agree. and per my last post, this may well be why Spears are OK with PTFE tape. The quality and conformity of their fittings is above average imo. Perhaps the worse fittings we have come across are the 'mega' fittings range. We once had a union roll off onto the workshop floor and split. We ripped it apart for a closer look and there were voids in the PVC wall!! I would think that more premium fittings are weighed during production for conformity.
But still the fact remains - PTFE can apply spot pressure to the female fitting which increases failure potential. And it will often drip if agitated after an initially successful seal. It's a common enough problem and if you google it, it's not hard to find examples and various experts explaining at length the reasons why it's not ideal.