I've recently seen here and elsewhere that irons only have one iron head (7 iron now) and how does one know how the PW or 5 iron will play. Seems difficult for trying a mixed bag of T100S and T200 when the lofts match. Let alone other combinations like T200 6-PW and T300 4-5 iron.
Clearly, 3-PW heads for 7 lines of irons and the correct length shafts would be overkill to try to fit every iron and have all the shafts available. I can't do the math on my fingers. But 500+ shafts would not be out of the question.
Opening the discussion - should Premier, Titleist Thursday's, and/or TPI/Manchester offer more like 5 and 8 iron heads instead of (just) 7? I can see that as an upside for marketing to better amateurs. But hard to stuff that many heads into a fitting bag at a retailer carrying clubs from 9 OEM that also only carry the 7 iron.