i'd do a grid where each square would hold 7. do you fold or roll them?

That's just short of a tee shirt a day for a year. 12 boxes with 31 hangers in each. Label with months. Allows room for expansion of the collection.

Sorry I never hang T shirts but the folding is a big deal . IMO drawers deep enough to hold the folded shirts is IMO a better use of space but who knows since we have no idea of the size of the closet or if ith holds other clothing too.I sure would not be moving a wall to hold Tshirts so maybe more info as to what the T shirts need this space at all.