One of the occupational hazards of playing for class too much is that you can end up playing in a way that only uses three fingers in each hand. After the 53rd group of people coming across the room in grand allegro, your hands start dabbing at the keyboard in an energy-saving position where most of the effort falls on the inside fingers. After a while, you forget what it’s like to play with all your hand at all. Ironically, the casualties of this are bass-line and melody, and that’s quite a big deal. Percy Grainger made a point of being very notationally precise about which notes to bring out or let recede in simple dance music like Country Gardens, and he’s one of the best models to work from, in my view.
It makes a huge difference to your sound if you start voicing chords with weight at the top (i.e. in your 4th and 5th fingers), and place your bass notes with as much care as if you were actually playing a double bass. It also begins to save energy, because instead of trying to keep up the same noise level for minutes at a time, you redistribute the effort to making singing melody lines and sonorous basses.
You can’t necessarily keep this up forever in a class, particularly on a terrible piano. But it’s a useful prophylactic against turning your hands into soft mallets, and the sound you get back is more gratifying, not just for the class, but for you as well.