Regarding frequency, I believe Ready to Run gives a sample program for what to hit when, and how often. Pain is one guide for what to tackle, and restriction another. For example, if you have chronically tight quads and hip flexors, then hit the couch stretch and smash your quads most days. Everyone has their specific trouble spots that need repeated attention. 

On to smashing frequency. Kelly has said in many Daily RX videos that you can’t overdo soft tissue mobilization. Two minutes is the minimum “dose” for smashing, tack and floss, pressure wave, banded distractions etc, but keep going as long as it takes to feel a positive change. Hence the “test and retest” philosophy – test a particular position to see how badly you’re restricted in it (such as the couch stretch) and use this as a guide for what you need to take action on. After you’ve done a mob – such as smashing the quads, re-test to see if you can obtain the correct position more easily. No luck? Then keep going. That being said, if something feels sketchy – such as if you get nerve pain or feel you’re about to dislocate a joint, then it is sketchy and you need to stop. 

These are all K-Star’s principles, not mine. I hope condensing/paraphrasing them helps!

Phil