Looking at my logbook, I've logged time with seven. However, that doesn't really tell the story.
Just over 29 of my 39 Pu/t hours were with the same instructor, who left at about the time I did my QXC - four of the other six were after that, while one was for my trial lesson and one taught me for three lessons at the start of the PPL before heading off to BA. So I had the same instructor for virtually all of the 'learning', and I think it is definitely an advantage. When you get back in the aeroplane you both know where you got to last time up, and you aren't going to spend half the lesson getting up to speed - and you're going to stick with one method for doing things, rather than finding that one instructor teaches High Key/Low Key PFLs and the other teaches Close Base leg (or Constant Aspect, or....)
However, in the late stages I got to fly with a number of different people, each with their own views and advice to give. That's a good thing, because by this stage you can learn without getting swamped with information - and no good instructor is going to try and change how you've learned PFLs at that stage unless you really have a problem...
