The FIRST kilt-esque garment I EVER wore was a Great kilt (though I STILL prefer the term belted plaid, or BP).
I bought 8 yards and tried to put it on. I IMMEDIATELY cut off 2 yards (which became my second hand-made, and first box pleat, kilt)! I the cut off more.
I also have one that is 3.5 yards! Here is a pic of it:


AND I have a 43 inch butt (hip)!

I prefer 4-5 yards for mine (I have a number of them).
One member likes 6.