Currently every day. I'm still doing injury recovery, but I suspect my PT will tell me to keep doing these every day. She made it very clear that I was to do these every day and twice a day if I wanted. "You'll do these tonight and every day. Every single day," was the exact statement, and I've followed her direction. My next appointment is next Friday.
When my pain got bad it was after only a half hour or so if running, coming from routine, pain free two hour runs only a week or two prior. For me it wasn't in my knee but instead in my calf immediately below my knee. It was extremely painful to move my lower leg forward. I could hold it straight and put weight on it, I could bend it back, but swinging my leg forward was almost excruciating. My PT suggested hamstring issues (it has been sore) with my calf then overworked to compensate.
I kind of thought my tight muscles were a sign of being very fit. Now I'm not sure that's true.