I think you may be able to get away with every other day, but I'm not sure. Either way, what matters is time and distance, and the total energy delivered.
You can deliver the same amount of total eenrgy, but one may be:
Short distance x Short time
Long distance x Long time
(because the amount of light energy falls off with increasing distance via the inverse square law)
And I'm not sure yet which one is better, but intuitively I would say that delivering a low dose anti-inflammatory effect just strong enough to suppress the damage from a longer distance (~20-30 cm) for a longer duration (20-30 minutes), does more for allowing the hair follicle to breathe than frying it way up close for 10 minutes. But I'm not sure yet, as I said. It's open for experimentation.
Also of interest is that I found that apparently red light seems to lower PGE2, I've found quite a lot of studies that support this. I can't find ANY data on what it does to PGD2, but about PGE2 it seems really clear that it gets lowered by red light, which would be bad in the context of hair (yet it has positive results on hair loss regardless). I think the reduction of PGE2 may be what limits the regrowth potential of red light. I wonder if you combined it with light dermastamping + PGE2 like
@westonci uses, if you could get really serious regrowth. Maybe something to try for someone with a good budget.