Like most everything about training to improve the overall ATHLETE, the distance running scene is about 20 years behind other sports.
You are always stretching muscles to a certain degree and always tightening muscles to a certain degree. This is how imbalances occur and how after 10-15 years of consistent running you "all of a sudden" are more tight, sore, and injured or you are always "working through issues".
The conventional thinking about stretching is wrong. Static stretching can do more harm than good unless you have a pre-existing issue. Dynamic movement is more effective.
1. Deep walking lunges: Take big step forward. Lunge down and forward while keeping back leg straight. Keep forward food on heel and back foot on toes. As you lunge down you should aim for your front hamstring to touch your front calf completely. You won't be able to do this as you are too tight and likely have an anterior pelvic tilt. To solve this place your front foot on a 4in rise. Alternate lunging with the right and left leg. Repeat 10 times.
2. Lying Leg pointers: Lay on your back with hands out to sides and legs straight down, like the letter "T". Bring left leg straight toward ceiling and swing it over to your right hand. You won't be able to swing it over to touch your right hand. Your hips are extremely tight. Alternate swing leg leg to right hand and right leg to left hand. Repeat 10 times.
3. Lying Knee pointers: Lay on back as above in the letter "T". This time bend your knees. Now take both knees and swing them to the left, then to the right. Repeat 10 times.
4. Elbow to Instep: Similar to a walking lunge with on caveat: Lunge forward, bring front elbow to front instep. So, if lunging with the right leg forward bring the elbow of right side down toward instep. Again, you won't be able to meet elbow to instep. You are too tight. Repeat for 10 steps.
5. Butt Kickers, High Knees, A-skips, Straight Leg skips, etc: All of these drills improve functional flexibility.
Static stretching is flawed because it is not dynamic. Your body functions through dynamic movement...not static stretching.