200mg/month seems to be the standard dose, no matter what your numbers are. I don’t even remember seeing anyone mention a different dose, though I’m sure there are some mavericks out there.
There’s no “official” testosterone level; every doctor can theoretically pick a number out of his hat. In practice, the insurance carriers have created their own separate tables of what amount of TRT they’ll pay for, in steps based on age. Due to the high “retail” cost, few people go past that.
And the older you get, the worse it’s stacked against you. The insurers base their numbers on an “average” they arrived at somehow, as opposed to “optimal.”