3 months seems to be my optimal duration for bulking. During these 3 months, I can gain almost all muscle as long as I already have a small layer of fat (~10-12%). After 3 months, gains turn to fat and my body doesn't seem willing to synthesize more muscle or increase in strength. This has happened 3 times before and I continued to bulk and gained fat the first two times.
2-3 months seems to be my optimal duration for cutting. After that, I start to lose strength like crazy. This has happened to me twice. I now know that I can only stay very very lean for brief periods, while I can maintain at about 8% just fine and neither gain or lose muscle.
Basically, I have an idea what my limits are now and I do not plan to go past my limits too much anymore.
After a recent long cut, I gained a great deal of muscle in only 2-3 weeks, similar to the ideas in the ABCDE diet. Taking advantage of this is very nice. Since that time, I have been gaining muscle with very little fat (with a one month interruption/layoff due to surgery). Now I am cutting.