let's say your gas tank carries 30 liters of gasoline... if you try to fill it up with 50 liters, you'll have 20 liters spilled all over the floor and you had to pay for it when it served no purpose... when you buy a new car with a 60 liter tank, it will still have room for more fuel even if you fill it up with 50 liters...
your gas tank is your muscle size... fuel is AAS... if someone starts off at 1000 mg, he will gain, probably more than someone starting at 500 mg... but his SHBG will be higher, which will basically hault his gains a lot sooner than if he raised the dose gradually. if he gets off for a while, allows SHBG to go down to normal, then he starts at 1000 mg again... he'll have more mass to start with, which will benefit from the higher dose, and his SHBG won't sabotage his gains as much for a while... and so on and so forth...
if he stayed at 1000 mg and never got off... yes, he'll have to increase dosages to counteract the SHBG... but where will it end? what could've been done at 1500 mg would take 3000 mg to achieve (just using numbers as examples and not a real live case)...
I probably wasn't very clear with this example... but you get my point, right?
if someone gets off long enough, he can go back to normal and gain on lower doses IF HE WAS USING MUCH MORE THAN HE NEEDED TO FROM THE BEGINING.
ofcourse, i don't have any proof of this