Discoloration is a sign that you have gone overboard. If you believe in the theory that PE is based on expansion that creates micro-tears that are not visible and then heal and you become larger, then discoloration would have to be labeled as macro-tears and ruptured capillaries that are visible and require more time to just heal the trauma back to normal and slow or stagnate the growth process.
Sure, some guys seem to accept discoloration as a part of PE, but that is only because they have never tried a more moderate approach that does not result in discoloration and actually generates faster results.
PE cannot be accelerated by going overboard and causing excessive injury and trauma. This is not no pain no gain. This is, if you have pain you will get no gain.
So take discoloration as a sign that you have crossed over your limit line and back off enough to stay below that line. You will get better results and still have a healthy and well functioning cock.