Dude1
I prefer to minimize the number of passes across the same area in efforts to minimize the risk of damaging remaining hair/prior grafts. However, each case has to be addressed on an individual basis and you need to address the patient’s need and explain to them the pros/cons of dense packing of grafts over a smaller area versus wider spacing of grafts over a large area with the plans to come back ~ a year later for additional grafting.
For example, if a Norwood VI came to my office I would prefer to plant ~3000 grafts over the frontal half of his scalp, creating a Norwood III-vee (vertex left untreated), rather then to plant the same zone with 1500 grafts planning another 1500 grafts a year later.
While this is my preference, you can safely follow the second approach. Also, you have to consider that some cannot afford the first approach. If this is the case, I feel you should wait ~ 1 year before the second surgery. By then all the grafts should be growing nicely and your worry about resting (Telogen) hair should not be an issue.
At any given time only ~10% of hairs are in the resting phase (Telogen) and while they are in the process of falling out most are still present and visible. The Telogen phase lasts ~ 90 days and it is not until the very end that the hair is shed. Also, most follicular unit grafts have multiple hair (2-3) so even if a FUG is in the process of shedding one of it’s hairs, the others will still be present, making it easy to avoid.
Brad Limmer, MD/jac

Dr. Limmer