The biggest problem or hold-back for most people is that they rush into PE and expect overnight results. I’ve been there and done it. The only result you get is injury which will make you question PE and whether it works. Slow and patient but consistent progression to harder levels is what will help you gain.
IMO PE method is very important and is something that will be different for each person. A method that may work for one person may not work for another due to physical or mental constraints. Again been there and done it - I must have tried so many different methods.
When you start gaining you know you are using the right method and are on the right track. My total gains are currently just short of 1.5” and simply accelerated in the last few months. It took me ages faffing around to find the method that clicked with me.