Ok, in a perfect world I would never have to write this thread, but we all know this isn't a perfect world. In the last week I have responded to 3 different guys who either ran their pct while on their cycle, ran the pct right at the end of the cycle before the suppressive compounds cleared, or thought if you used serms or ai's on cycle then you didn't need a pct.
Let's back up a bit and explain why we need pct and what it does. Our bodies attempt to keep a natural balance of hormonal levels. When we inject steroids, our bodies sense the presence and recognize it as elevated testosterone levels, therefore the body lowers or ceases it's natural production. Our bodies also attempt to keep somewhat of a balance between testosterone and estrogen, that's why the higher testosterone levels may lead to increased estrogen. Now I'm certainly no doctor, and my brain often works like a cartoon, so I'll explain what happens in cartoon fashion. After you finish the cycle and the suppressive compounds clear, we take serms, which go up and tap on our brains and say "hey dumbass, produce some more testosterone". our brain looks and says "oh, my bad" and the process of restoring our natural levels gets a kick in the pants. Now let's assume we start our pct while on cycle or before the compounds clear our system. the serm makes it's trip to our brain and says "hey dumbass, produce some more testosterone", the brain checks and sees what it feels is an abundance of testosterone, and tells the serm "hey fvck off mate, you aren't the boss of me". Of course the serm does other things, but this is my cartoon and I'm keeping it simple.
To summarize, the ability of pct compounds to restore our natural testosterone production is no match for the extremely suppressive nature of the steroids we inject, so to start pct before the suppressive compounds clear only wastes the pct chems and makes for an inadequate and unsuccessful pct.