I've been using the Hannon ones for years whenever It's been awhile since I've played seriously that seems to build up my hand strength in ways it needs to be built up. Now I know that several well known composers have etudes that are supposed to be kind of like it. I've wanted to fiddle with the Debussy ones for years, but never gotten around to it, maybe it's time? Will they help? They show off different ways of playing with chords and single notes. I don't know how it will help with finger and hand strength.