LOL You know what they say? Flattery will get you everything.

You should always be careful when engaging in any BDSM activity, whether it be binding breasts or just simply kneeling for your dominant's pleasure.

I mean, it is conceivable that while attempting to kneel, you could turn your knee or twist your ankle. While kneeling, blood flow is restricted from your feet, just as it is in breat bondage (only with the breasts and not the feet). This can cause problems, but is not likely to be threatening unless you plan to kneel for like a week at a time.

I think probably the best way to judge when to take the ropes off is by using common sense. Go by how you feel, first and foremost. If your breasts don't feel "right" or are numb or cold, then tell your dominant that it's time for the ropes to come off.

Your dominant should also be paying attention, too. If he sees some of the obvious signs of blood flow restriction, then he should use his common sense and remove the bindings.

It is unsafe to leave the ropes on for as long as what you saw in the pictures featuring the dark purple breasts, but it is not likely to be a serious health risk. Do you really want to take the chance, though?

I usually just look for the start of them turning purple and then I will disengage the bondage, unless the scene we are doing calls for more lengthy and elaborate work. I might leave the bondage on longer in that case just to set the mood a little better.

I would never leave any bondage on long enough to permanently harm someone, though. Loss of blood flow can lead to tissue necrosis and can cause the skin and outer lying tissue to slough off like a snake's skin. It's very, very unpleasant.

Don't be too paranoid with my advisories, though. Try it for yourself and enjoy. Once you practice it for awhile, you will learn what works for you and so will your dominant.