He actually splits the 10,000 grafts in 2 two-day sessions , many months apart.
Still risky because the sessions are still fairly big (around 5000 grafts or more) and there is always the chance something out of the doctor's control going wrong and you will end up losing a sh*t ton of grafts. If I go to Dr. Zarev I'm thinking about asking for the procedures to be split in more smaller sessions to lower the risks.
There is a case in the spanish hair transplant forums where a guy had around 3,000 grafts with Dr Bruno Pinto (a very good hair transplant doctor) and basically none of it ended up growing. Later on he found out he had a condition in his scalp causing an auto immune disease that probably nuked all the implanted grafts. Imagine if he had done one of those giga sessions before finding out about it. All his donor would have went to the trash.
Here is the case :
https://foro.recuperarelpelo.com/viewtopic.php?f=16&t=78822&start=615