I’m glad the link I provided worked for you, I had the same thought when I saw people suggesting using a saw blade. You have to be a special kind of crazy.
I talked to a massage therapist about this very question. He specializes on athletes and works on professional and college runners here in Boston. He said it to use the massager for 24 hours after a hard workout, much like a TDF rider doesn’t get a deep tissue massage after stages. So I use mine on my off days and stretch on the nights I workout. He argued that your muscles are attempting to heal after you workout and the massager is breaking up knots and not allowing your muscles to heal.
Hope this helps.