Working with my massage therapist, I was told that you should extend until you feel the full tension/tightness and hold it for 45 seconds. This will provide positive effects of relaxing that tension for a few hours at a time.
I stretch before exercise and after. I stretch all over and concentrate on my hamstrings. Other times to stretch is after sitting for a long period and right before bed because it relaxes my body.
After swimming practice. I have two hours swimming and my muscles are so tired after that. I usually stretch for 15 minutes through whole body
I stretch before bed. Depending on the night, I’ll stretch for as long as 5 minutes. I listen to my body and decide what needs to be addressed each day. I’m at the gym each evening for 2-3 hours so this doesn’t include the time I spend stretching pre/post workout.