TL;DR1: Frequency is way more important than duration for improving range of motion. The most effective stretching requires only five minutes a week, but done over at least six days during the week. More than 10 minutes per week is wasted effort.
I often suggest stretching to clients as a way to keep working with a tight muscle between sessions.
I came across a video on the Physics Girl YouTube channel that explores what are the actual physiological effects that stretching has on the muscles, ligaments, and tendons. I thought it was interesting, particularly in how little you actually have do to make stretching work well.
The Physics Girl channel on YouTube is hosted by Dianna Cowern and presents unusual topics about physics, astronomy and science in everyday language.
“too long; didn’t read.” Or watch. ↩