What you need to know is that "absolutes" are extremely rare. The answers almost always lie somewhere in the middle. Some people will need their hamstrings left alone almost all the time, and some will need their hammies worked on often. It completely depends on the individual.
Our main focus during the screen and assessment that tells us what we need to know concerning the hamstring almost always comes from:
- The alignment of the hip: anterior/posterior/neutral pelvic tilt
- The symmetry between the flexion and extension patterns of the Right and Left leg
- Asymmetries are actually the 2nd biggest predictor for injury, the 1st being pre-existing injury
- It has NOTHING to do with a sit and reach, that is a low back test, not a hamstring test
When Stretching the hamstring, where the majority of the world goes wrong is using a touch the toes or a sit and reach approach, both are terribly incorrect with regard to the hamstring. Yes they do have a place, even though it is rare and should only be used in assessments such as the SFMA, which is an incredible way to look into what's going on with a person in pain. Practicing these movements and stretches is an entirely different deal.
When stretching the hamstring, we want to support a proper spinal alighment. In order to improve this stretch use a towel under your low back.
If I were to show you my other leg in this video you'd see why I need more work on my right side and less on my left.
Keep in mind that most people actually need very little hamstring stretching, and the ones that do usually need quite a bit of it. So it's going to be a good idea to get assessed in order to adjust your actions with your needs.