4 weeks, 6 week, 8 weeks? Depends on what you are looking for and genetics. The shorter the cycle, the harder it is to maintain gains. Your body is going to try to remain in staisis, and the longer you can hold on to your gains, the better your chances of maintaining them. There is also a large genetic factor involved. Some people can hold on to gains easier than others. For those people who have a harder time holding on to mass, longer cycles are going to be of greater benefit. However, longer cycles have a greater impact on GnRH and thus can be more difficult to recover from.
Best legal approach to recovery? If you consider yourself a reasearch project, Liquid Clolmid or Nolva. Otherwise, 6-Oxo. I have tried 6-Oxo, and it is effective.