1. Creating situations likely to lead to poor recovery of natural testosterone production
2. Uncontrolled high-estrogen situations
3. Overly-prolonged use of alkylated steroids, and
4. Inefficient use of time.
The first is affected principally by cycle length. Very short cycles of only 2 weeks never, so far as I have ever seen, lead to any issues with recovery of natural testosterone at all. With regard to more typical cycle lengths, I’ve never seen an issue with 6 weeks although recovery can take a week or two and is generally faster than with 8 weeks. Eight weeks only rarely gives slow recovery, 10 weeks more frequently does so, and 12 weeks is still usually okay but is yet more likely to give a slow recovery. Exceeding 12 weeks gives much greater likelihood of slow recovery.
A second consideration in avoiding poor recovery is to avoid allowing testicular atrophy. With cycle lengths of no more than 8 weeks, it’s rare to have an issue here. One might choose, though, as a guarantee to use HCG during the cycle or in the last few weeks. Where cycle length exceeds this, I’d definitely recommend avoiding testicular atrophy by such use of HCG.
A third consideration is avoiding use of Muscle powder Deca, or if needing it for the joints, avoiding dosings above 100 mg/week and preferably a bit less.
Lastly in this regard, certainly avoid failure to do PCT.
High estrogen situations are caused by relatively high usage of aromatizing compounds. One method of control is to use an anti-aromatase dosed so as to maintain normal estrogen levels. Another, less recommended, is to use a SERM to block the effect of high estrogen levels on tissues such as breast tissue. Either use principally non-aromatizing steroids and only a personally-acceptable amount of aromatizing steroids, or if using more aromatizing steroids, then use an anti-aromatase such as Femara Letrozole or Arimidex Anastrozole.
With regard to liver safety, avoid using alkylated steroids for more than 6 weeks, or 8 weeks at most. Six weeks is definitely the more conservative approach. Cycles can be planned where injectable dosing is higher during the weeks without orals, so gains really do not have to be compromised by taking this care.
With regard to inefficient use of time, avoid spending more time than necessary at levels which are less than you’ve chosen for anabolic effectiveness yet still too high to allow recovery. An extremely important method of increasing efficiency here is to frontload on Day 1 of the cycle. If failing to do this, commonly about the first three weeks of a cycle are largely wasted. A second method is to use shorter acting steroids at the end of a cycle, or throughout the cycle, to make a fast transition between anabolically-effective levels and levels which allow recovery.