I had a regime of triple binding - Underworks 997, with a tri top over the top, and then the 997 folded back over top. I did this for 4 months, 6 days a week. I used to get cute from the binder edges so used to put plasters on the rubbed areas. I often felt sick and short of breath but as someone has mentioned already, the physical pain didn't outweigh the mental pain of not doing it. I had surgery 3 months ago and the extreme binding didn't seem tO have had an impact.
Anyway my point is that I did it, nothing bad happened, and it really helped my confidence despite the pain... Just to offer my 2c.