I also stretch after to relieve some tightness, increase blood flow and give the lactic acid room to drain quickly.
I stretch a lot
It's good to stretch before and after your workout.
I normally do about 3-5 mins of stretching before working out.
Then a 10 min walk on the treadmill or outside. Or 3-5 mins in a dry sauna fully clothed. Both help to warm up your body before a a work out.
Then about 5-10 mins of stretching after working out.
After is part of the cool down and makes sure blood is getting through all the vessels it needs to, and lessens the chance of stiffness or soreness centralised in muscles