here is my take on this. i think for someone in their mid 30 you could save a lot of grafts if you have a more conservative hairline. i also think in order to properly frame your face it could be argued that a thin spot at the crown would be acceptable, a normal look past 30 and can be covered well with toppik. that again would save a lot of grafts.
however!!
i think the bigger problem is the fact that not having to use finasteride because it is donor zone hair is not completely accurate especially in younger men. many report a thinning of transplanted hairs. why? well first of all, what can be found in the frontal scalp is an upregulation of dht. when you plant the hairs from the back to the front they are susceptible to more dht, some still express the androgen receptor, studies have shown that even the donor zone in men with Androgenetic Alopecia thins out ovet time just much slower. however in an environment with higher androgens this can happen quicker.
furthermore, the surrounding cells are still susceptible to the balding process, there are signaling molecules being produces in their roots that have inhibitory properties, these are paracrine not just autocrine signals and thus, it can have an effect even on the neighboring cells. that means your non transplanted scalp is killing your donor hair.
when you are old and your balding process has been arrested for a long period of time this might not be w problem. however note that in older men gair generally becomes thinner. when you have such a tranplwnt you cannot afford any further thinning
my opinion is, a full transplant is not feasible past Norwood 4 if you hwve non insane donor area. hopefully soon we have drugs that might not give full but at least partial regrowth so that it can make non candidates candidates and also arrest the balding process further so that groeth inhibitory paracrine signals from cells nearby(there was a talk from the hair loss congress 2020 thag went into depth on this and why transplanted hair can get prone to minatutizatio) are not an issue