I disagree.
Changing schools may be the best thing you can do! Getting experience from elsewhere, new aerodromes, new planes, new instructors, new procedures are all good things. All experiences are good to have under your belt so that you will be a better, safer pilot.
I find that schools are only as good as the particular instructor you've secured a good relationship with. And that instructor is often (but not always) as good as the management supporting them. Most schools / clubs have both some (but few) fantastic instructors and some relatively mediocre (or sometimes bad) instructors.
My recommendation, is the same as always. Find the places closest to you - but a trial flight with each and get a vibe for the instructor and the place. It might be a little more costly, but at least you won't settle for second (or worse) best!
Hope this helps!