I have been trying to tell my students about this for years. When I was in my training there was this guy that could consistently turn 7 or 8 times on command. 99% of the time he could just do the most beautiful 7 or 8 pirrouettes, I on the other hand was struggling with triples (still am depending on the day
Anyway, I finally asked him one day about how he developed the ability to execute pirrouettes so effortlessly and here is what he said;
"get a video of white nights where Barishnikov does the 12 pirrouettes or any video of somebody who does nice pirrouettes, turn off all the lights in the room you are going to watch the video in and just watch the pirrouettes over and over again for atleast an hour."
I tried it myself and much to my surprise, it works, well. I have ran into quite a few dancers over the years who use this exact same technique to help enforce their turns.
As dancers we are constantly learning movement, choreography and technique by committing what we see to memory. If we see something repeated a couple of hundred times and really try to committ it to memory our bodies will eventually begin to mimic what is in our minds.
Then again there is no one exact way to do pirrouettes, IMHO of course, it is an individual thing, as I always tell my students, "whatever gets you around and practice makes perfect".