Static, passive stretching can and imho should be done as often as you like and is possible. The only thing you would want to regulate is if you do any isometric stretching; that is breaking down muscle tissue just like any other resistance training and should have recovery time involved. Dynamic stretching, moving stretches we call high front stretch, high side stretch and so on, should be done before training and I've found to be helpful doing them 1st thing every morning to start the day. Just don't go crazy with them. It's not throwing your leg as hard as you can towards the sky but lifting it to it's limit and releasing it until you reach your optimum height.
p.s. this is all out of Kurtz's "Stretching Scientifically" and not my own personal revelations. But, I've found it extremely useful.
There are no PERFECT techniques, only perfect execution for the situation at hand.