Pleater makes a good point, and it's a reason NOT to buy tartan with a set less than 4-inches. 4.5 inches is pushing it, IMHO, 5 inches is fine, and 6 is great. If your tartan is less than 4 inches in the sett, you'll be pleating double-setts. That's OK, but you'll need more material.

In My Humble Opinion.... I am no expert, eh?

Anyway, here's the point. If the sett is 6 inches, then let's work out how deep the pleats will be, if you use a 1 inch reveal.

OK, the reveal is 1 inch. That leaves 5 inches for the rest of the pleat. That will be divided in half, right? So that means that the "depth" of the pleat is 2.5 inches. Get out a ruler and look at that. Hmmm... OK. 2.5 inches is a fair bit, eh?

Now how about a 4.5 inch sett? If you reveal 1 inch, that leaves 3.5 inches for the rest of the pleat. Ooooo...so this pleat is only 1.75 inches deep. That's not very deep. It's OK, but I sure wouldn't want to go any less than this. My Holyrood 5 yard from Caledonia kilts is like this. It looks good.

My Stillwater Black Watch has a 4 inch sett. The reveal is about .5 - .6 inches, and the depth of the pleat is about 1.75 inches. It has 33 pleats. The pleat depth works OK, but at least my Stillwater has a double-depth (two seets) deep pleat about every 5th pleat. This adds weight. Basically the way they get away with the small sett (4 inches) is by putting in more pleats, and therefore using small reveals. This makes the pleat depth acceptable.