TRT/HRT/cruise used to mean test levels within natural reference range but the BB community has largely shifted to define TRT/cruise as ‘test dosage/levels that may be supraphysiological but still allows relevant blood markers to recover/stay in healthy range’, so I’d argue the healthier your lifestyle (cardio, nutrition, sleep, low stress), the more you may be able to get away with.
I can see 250-300mg being possible, if you need more than that to maintain size, you’re likely so heavy anyway the sheer amount of your bodyweight (muscle or fat doesn’t matter in this context) alone will put stress on your heart/system, and so I’d actually argue for losing size/weight now and then like the BB of era’s past did when going off cycle - by their example you can see as well how quickly they were able to regain all of their size back when getting on cycle again, so that’s not an issue.
The larger argument would be: Is it best for ones health/system to maintain a certain size/state (homeostasis, avoiding negatively stressing our system) or to be ‘flexible’ (hormesis aka adaption through positive stress, related concepts of metabolic flexibility and a circadian/seasonal rhythm akin to our ancestral lifestyle up until we had to adapt to the seasons of the year and thus changing environments etc.)