I burn in my headphones usually at night while I sleep for as many days as I think they benefit from the excercise. I rarely burnin headphones this way for anything more than 100 hours unless I am not enjoying the headphone and am hoping the additional burnin will help. I also like to listen to my headphones as they burnin in which is why I usually only burn them in at night and listen to them during the day.
I do like to use combinations of different type of noise combining brown, pink, and white in larger or lesser amount depending on which area I think the headphone needs the buggest improvement. I also have incorporated cymbals and heavy drumming in some tracks as additional stress in thoese areas specifically. But I also have a bunch of regular music I have combined into a play list that I use for burnin especially if I find my burnin files seem to be affecting the headphones in a way I find undesirable that way I eliminate that possibility and continue to excercise the headphones at night.