That's helpful, thank you.To be honest, we don't have much experience with pre-stretching our polys. One of the reasons why we don't experiment with it is since it will change the actual playing experience from what the string was intended to play (not to say that a pre-stretched poly will feel just right for some players).
We know how our strings play at a 52-48 lbs tension very well. This helps us to give pretty accurate string recommendations if we know our customers' playing level, age, preferred string characteristics, etc. Adding another dimension (recommending to pre-stretch a poly), would make recommending a string even more complex and potentially confusing.
Apologies for not being too helpful on the topic!