I think we all agree with Carlisle (awesome), Ted and CPE Bach - improvising is the way to attain a high level of technique. I'd better make a start.
outin - my teacher (the only person of many piano encounters I would give that name too) knew all the problems of the repertoire, so we went straight to those - the 10ths in Beet's op 90, Schubert impromptus, that kind of thing. It would take me some time to dig up what we worked on. Every now and then I open a book to find her writing/fingering inside and it all comes back. The only technique I learnt was where to relax - not as simple as many think. It took me 5 years to relax.
I do have the suspicion that much of the activity described as technique by students is actually ligament/fascia building to accommodate modern concert pianos - which takes me back to that poor little kid on page 1!