There is no reason to have tanks or healers use static positions.
Healer with searing stands to the left at all times, healer who is free stands in the middle so he doesn't need to dodge and can plant themselves for healing. DPS stand on ifrit's right leg and run eruptions along the edge of the right side of the arena, making it so the healer NEVER has the move for them. During nail phases 1 and 2, the first healer with searing goes left, the second searing goes right as people swing around the arena to clear nails on the left since they are going right > left. For the final nail phase it's the same thing but left x2 > right.
Off tank stands on the left leg so that when OT eruption happens no one but them has to move.
This way the healers are the ones doing the majority of the moving, and it insures no one walks into anyone on accident unless they're really not paying attention. It also frees up tank movement so that they can help on nails and healers are able to move with the group when they do not have searing for AoE heals.
XI Wiki



