... Can you explain the way shbg works? I am confused with how a low or high shbg works with shots?
SHBG binds to testosterone, thereby making it last longer. For a given total serum testosterone, higher SHBG means less free testosterone. Because free testosterone is the form that does useful stuff, you do not want SHBG to be too high, because it suppresses free T. But at the other end, when SHBG is too low then there's too much free T, at least relatively, and it is used up too fast. So a guy with high SHBG might inject testosterone weekly and not have serum levels drop too much by the time of his next shot. But a guy with low SHBG could see his levels decline dramatically if he waits too long. And he can't inject extra testosterone because then his hormone levels, including estradiol, go too high shortly after the injection. This is why, in general, frequent, small injections are preferred for guys with low SHBG.
***Edit: In this and some subsequent posts I repeat the mistaken idea that SHBG influences the apparent serum half-life of testosterone after injections. In fact, the apparent half-life is mainly dependent on the rate of absorption of the injected depot. Nonetheless, there are many anecdotal reports of men with low SHBG doing better upon switching to smaller, more frequent injections. The reasons aren't clear, but a reduction in peak estradiol may be one of them.