i'm not saying you can't have your breasts bound for 30 minutes, as i've had mine bound that long as well. but you can be damn sure that the second i saw my breasts starting to turn purple, pain or not, the scissors would be coming out. actually, i'd probably stop them while they're being bound if i knew it was too tight.
does this really look safe or sane to you???
you and i have very different ideas of safety. position yourself that way and blood is not going to pool in your breasts. the only reason it's pooling is because it can't circulate because your breasts are tied too tightly. as i mentioned, even your arms are starting to turn purple.
if i were at a party and saw someone's breasts and arms turning purple, you can guarantee that i'd be consulting with a DM.