I usually hear time lifting used to determine if someone is ready to use AAS. I never really saw this as being a good way to determine this. We all know people who have been lifting for years without much to show for it. Why not use overall strength? For example, we could say you are not ready for AAS unless you can bench 1.5 times your bodyweight and squat 2x, etc. We could debate those numbers, but it seems like this would at least be a better way to determine tendon strength and how close you may be to your natural limits, and attached a numeric factor that could be measured.