Thanks for the very detailed answer, Observer! And a clear and detailed answer was indeed needed for this.
I would like to make a precision, for other members who would want to try: you have to be aware, that, for Observer, niacin is effective in the first place, and has been for many years ( I even included him in the list of reference members for success with niacin, in my POIS types chart - see
http://poiscenter.com/forums/index.php?topic=2338.msg19448#msg19448 ).
So, if niacin is not effective to prevent POIS for you, for a single orgasm, it obviously won't be for a second one, or it would otherwise defy logic......
If you never tried niacin before, I suggest you first try niacin before one single release, and see what it does for you, before trying the Observer protocol for "second orgasm on niacin to eliminate POIS symptoms of a previous first one"
Even if you have some success with niacin, usually, this does not mean, anyway, that you will have the same beneficial effect as Observer has for a second one.