Anything that makes slow, deliberate, lean gains is easier to keep.
Type I activity is also easier to keep.
My theory is that people who think they have lost alot muscle post cycle with test and dbol and other common compounds, have merely lost fullness and pump, and retained water in the muscles. Pair this with the loss of strength from the androgen not being in the system and you feel like you have lost 5 pounds of muscle.
When really you have lost 5 pounds of mostly water and androgen induced strength.
That muscle you "lost" never really existed in the first place.
Do you lose muscle ? Yes, is it usually dramatic ? Not if your doing everything correctly or are far above your genetic limits.