THe longer u run the longer its going to take to recover. U dont lose muscle when u come off longer than normal cycles 8-12 weeks. Id argue that 80-100% of what you gained for muscle on a cycle (especially test cycles) stay with u. Just cause ur not injecting doesnt mean ur muscles disappear. Steroids increase protein synthesis and nitrogen retention, they trigger the body to build muscle, but muscle is built from proteins (and some fats and glycogen). The ceaseation of steroids doesnt mean ur going to shrink (especially with the use of PROPER PCT).
THis is what i think (and i have finished a test cycle and gone thru PCT so i have SOME exerpeince maybe not as much as others), if you are ameature and want to do something more with your life than bodybuild or powerlift, 3 month cycles should be fine for you. You should be able to gain rapidly and efficiently and not be shut down for so long that ur body forgets what natural FSH and LH is like, or how to respond to it. You should be able to recover basicly pretty quick and be able to be back to normal pretty fast.
NOW if u wanna be my.Olympia or the next MET-RX strongest man. YA u gotta go on, and i mean for years, And HRT is going to be the PCT, cause there is almost no way to come off of a 3 year binge and try to even start ur HPTA back up.
6 month cycles? Ya u could probably do it, u should be running way more than just test if ur running for that long tho, u might as well stack and get the benefits of the test making u feel good while running harsher compounds. Could u PCT and get back to normal Probaby depends on age, genetics, and prior steroid useage.
If there where an age to do it i would say the younger the better, youth brings along a lot of ability to recovery from dumb things and i would say u would need it for a hard 6month-a year cycle.
All in all If u wanna go pro ur gonna need to do it longer, if u dont keep it simple and easy to recover from unless HRT is something u dont think u would mind doing.