About twenty years ago, before I was enlightened about the risk of injuries when I practiced and how to avoid them, I sustained a ligament tear of my ring finger, right hand. It was while playing the Schumann Carnaval, and just before it happened, I had held my hand in a rigid arched position anticipating a stretch of notes well beyond the octave. It was definitely a suicide gesture to attempt to accommodate the large spread of keys with a traditionally, boxed in, ultra round-shaped hand.
After my ordeal I no longer advocated a “fixed,” unaltered hand position, and I made sure to teach my students ways to protect themselves from practice-related injuries. (I recommended “Warming” up gradually– playing scales and arpeggios in slow motion, breathing through groups of notes, and enlisting a rolling, curving motion)
To prevent finger tears, carpal tunnel and the rest, I advised that students should have very pliant, flexible wrists and hands. If there’s a big keyboard span to tackle, it’s best to use ROTATION without tightening muscles. Gently ROLLING between notes over an octave is the best approach as I demonstrated in the embedded video.
Using longer or broader fingers when attempting to play large intervals, is a hand protector.
Having natural follow-through motions while navigating the expanded intervals is another way to lower the injury risk.
As for over-practicing day in and day out, such excess might lead to nerve damage, carpal tunnel, etc.
I’d once practiced the same trills for hours at time, having to seriously consider a red flag warning: achy hands.
Once the body is telling the player to give it a rest, he/she should heed what’s in his best physical interests.