When I came back from the US with my shiny new PPL I'd only ever flown with one instructor for teaching, one for a pre-solo check flight and the examiner.
The club I joined quite rightly checked me out, now I hated the idea of flying with a different instructor - more to do with my lack of confidence than the instructor. In the following three flights I had three different instructors. By the third one I hadn't even been allowed to taxy before I was being 're-taught' his way. I had a small hissy fit at the hold. Pointing out that it might be helpful to let me do it my way. If I was doing something downright dangerous then tell me, but could we maybe discuss it at the de-brief as to the variations in methods rather than reteach me all the way through the flight. Which is what we did and it worked.
This has not put either of us off. This guy is a brilliant instructor, all of them at the club where my shared aircraft is based are great. They are all approachable, will offer advice should it be sought without condescension or patronisation. Ages vary, and yes, they have either gone to the airlines or are heading that way. But three years later having now got over my issues, I seek these guys out to go fly with them. And they are quite happy to put up with me and will come fly with me on their days off. I learn something every time I fly with them - it also means that my revalidation flight is not a scary proposition.
The situation we have is in the minority but it shows that it can exist if the various personalities allow it to. The FI's have done different courses, learnt different techniques and like MJ points out in the other thread it does cause lots of issues with the students. Then throw in some of the examiners personal likes/dislikes and that's a whole new ball game.
As PPLs though, we shouldn't think that the learning stops the day we got our shiny licence.