Quite a few people do hCG mono therapy, but in order to achieve high enough T levels some people require dangerously high doses of hCG that can lead to gonadotropin receptor desensitization.
KSman's point about aromatization in the testes is valid, but it isn't that intratesticular testosterone (ITT) aromatization isn't afftected by an AI at all. It is affected. It's just that ITT concentrations are so much higher than serum T concentrations that ITT aromatization happens at a higher rate and is harder to control. Since an AI will exist in the testes and the peripheries at more or less equal concentrations, it is easier to compete with T for aromatase binding outside of testes than inside (assuming our AI is a reversable competative aromatase binder, like anastrozole).
If you take a shit tonne of AI you can definitely shut down all estrogen production (intratesticular included). And you will feel terrible. But more importantly, even if you take an AI at a dose that allows for IIT aromatization but shuts down peripheral T aromatization (like 1mg Anastrozole per day), you will feel terrible.
It's not enough to have a good E2 level (ie, high AI and really high hCG to jack up ITT), the E2 needs to be synthesized from T in the right tissues. Your brain cells, for example, need the aromatization T->E2 to actually happen locally (inside them) for certain processes to proceed normally.
That's part of the reason why it is recommended here to take T, hCG (low dose to keep testes running, but not jack up ITT), and adjust AI as needed.
The other thing to consider when adjusting anastrozole dose is that you likely won't even start to feel a true affect of the drug for three days or so after you take it. So if you are taking it at the time of injection, you want to give yourself at least a week before you even start to think about how you are feeling. The are so many things that can give you the same symptoms of high/low E2 that you want to gauge how you feel on average over the course of weeks, not hours or days.