I guess most would consider the peak of the rut to be 4-5 days when the majority of does in the area are in heat. Now of course some does will likely have come into heat before this and some will come into heat after this. Many times, there will be a second rut, when many of the yearling does will come into heat. I have never witnessed this though since our season ends in mid-December right after the rut. Anyhow, once the peak of the rut is over, a bucks patterns kind of go back to how they were in pre-rut, scraping and rubbing is more intense, so scrape lines aren't a bad idea as a spot to hunt. Anyhow to answer your question, I don't think there is a definite asnswer other than "it lasts till all the does are bred." You just got to keep an eye on the deer and on the sign.