by godawful crash i mean that there will be a longer period that your natural test production is offline. during this time, dose of synthetic test is so low that it doesnt stop catabolism or oppose estrogen related side effects (possible gyno, water retention, fat deposition, muscle softening) and your natural test isnt there to do its job
in the perfect cycle with perfect pct, you get a full 10 weeks (or whatever) of lots and lots of test floating around in your blood making you grow like a weed. at the end of the perfect cycle, you have a period in which your synthetic test has to be stopped in such a way that the administration of anti estrogens like nolvadex or clomid will perfectly stimulate natural test production, increasing natural test to such a degree that your body goes back to how it used to be. ie you keep all the gains after that point.
now the success of this transition will depend on 2 things: 1) how supressed your test production is (which mostly depends on how long you were supplementing synthetic test for- the longer, the worse the supression) and 2) how well you time the dose of nolva or clomid to coincide with that exact point in time where the levels of synthetic test are equal to the levels normally seen in your body (if you use nolva/clomid too late, you will have experienced a short interval where your overall test is very low, and so you will get the symptoms of "crashing"- muscle loss etc etc)
now if you have a nice, rapid drop off of synthetic test, then you can guess pretty accurately when your synthetic test will be about equal to normal endogenous test. therefore you will stimulate your testes just when you need to, and things will return to normal nice and fast, with minimum crashing.
if you use sustanon or something, it drops down so slowly that you have no idea just when your synthetic test levels will drop to a level equivalent to normal test levels. so when the hell are you supposed to start pct? unless you have access to a lab, you have a good chance of timing it wrong. therefore, logically, you will likely go for a much longer time with sub normal test levels before doing pct (you will do it late and therefore crash harder) OR, even worse, you will do your pct way too early, while your synthetic test levels are very high, making the pct ineffective, and making your end of cycle to pct transition similar to not doing pct at all.
timing is everything gentlemen. the smoother the transition between synthetic test being all that is in your body to natural test once again being the test in your body, the less time you will have to endure havnig low low test and high high estrogen, and so the less time you will have where you are crashing, and burning all the benefits of your cycle
if thats not clear enough, post up ill try to clarify
by the way, if there is a mod about, how do you feel about giving me the title "pharmacist" or something. not because i want a cool (lol!) title, but so that i can stop having to say it all the time.
cheers