I already had two sessions totaling 6000 grafts so far, can I do another 4000 grafts? (photo)

FUE has more limits to donor area harvesting than strip surgery does. FUE, depending upon the donor density, can rarely exceed 4000 grafts safely without depleting the donor area visibly, while Strip surgery can often go as high as 10,000 grafts if your donor density is adequate. I wrote a paper on this very subject, see here: https://baldingblog.com/2017/07/21/many-fue-grafts-many-fues-grafts-one-know-safe-limits/. You don’t have a see-through your donor area and you were not specific as to the type of surgery you had (FUE or strip surgery) but use the guide in the article and your doctor’s advice for determining your next step.