On the practical side, my urologist has patients that only respond when their total is 1500 or higher and it's a given that their free T is also high. The reasons why some men only respond to high doses of testosterone, whether injected, topical or pellets isn't really known and the knowledgeable doctors who prescribe TRT, will treat until there's symptom resolution. I referred to an abstract in Frontiers of Immunology about vitamin D resistance and the two possible causes stated are either VDR polymorphisms or pathogens that block or blunt vitamin D receptors. And the way to treat is to keep titrating until the resistance is overcome.
Whether in the case of testosterone or vitamin D or even thyroid resistance, the only practical way is to push the dose but, in the case of testosterone, there could be deleterious effects or problems from prolonged high dosing. It isn't perfect, but until the underlying mechanisms of resistance are discovered and can be corrected, treating until symptom resolution is all we have.
You need to keep in mind that most are not being treated by doctors in the know let alone have no clue how exogenous esterified T works.
Unfortunately, most are caught up on the more T is the better mentality let alone many are jacked up on T from the get-go.
Top it all of that whether one is starting trt or tweaking a protocol (increasing dose of T) many never give the protocol a fighting chance (12 weeks) and are destined for failure.
You know the ones upping their T dose every 6 weeks because they do not feel well!
These are the same men chasing their tales endlessly caught up on that never-ending. merry go round
Many also tend to have unrealistic expectations thinking high T levels will cure everything that ails them.
These same individuals get caught up searching for something that will never be there.
Although symptom resolution is what truly matters avoiding/minimizing sides let alone maintaining healthy blood markers long-term is key.