Forget exercise books--all of them. Concentrate on all scales (four octaves in parallel) and arpeggios, major and minor, and be able to play them well through the Circle of 5ths either downward starting on C, Am, F, Dm, etc. or upward beginning on Em, G, Bm, D etc. Also be able to play any scale at random. Learn the chromatic scale as well. Find one, just one (not a book full of them) effective independence of the fingers exercise where each one of the fingers holds the anchor position in turn while the others play around it, and use that as needed. This is all the technical regimen you'll ever need. Learn and improve your technique in the real world of music during your practicing of actual repertoire pieces. Let the master composers teach you. Every time you solve a particular technical problem in a piece, such as smoothing out a short cadenza, managing melody and accompaniment within the same hand, perfecting execution of a polyrhythm, voicing melodic chords, playing important inner lines, or whatever, you have effectively advanced your technique WHILE learning and expanding repertoire. It's a far more efficient and productive use of your time.