Dr Zarev doesn't take consultations any more because his clinic is booked up so much. I think that there isn't even a contact email address there anymore. There, they got over 11,000 grafts. For me, every clinic has said that they can get around 3000 grafts from the scalp. Even with Dr Zarev's potentially superior extraction methods, they won't be able to get more than double 3000 = 6000. This guy has gray hair so it looks like he's an older guy who has been able to maintain his donor over time. They told me that they wouldn't extract much from the sides above the ear, as they did for him, because it's thinning and not safe. In addition, my sides may be dropping lower; there is some thinning there around the horseshoe (on top of the retrograde described in the previous sentence).
If you want to cherry pick good candidates then go ahead. We know that the best doctors can do incredible things with good candidates. With enough donor to work with, the FUE doctors are doing absolutely incredible things. They can't do that with a bad candidate.