One or two can easily be left out. It's often the viso that's left out because there's much less variety of it available to us. Some guys don't like ligero and so they avoid it; some guys don't like seco and so, if they have burny ligero that's all they'll use. The Illusione dude, Don Giolito...
You gotta burn test them. You can't just go on thickness. Always know the burniness of each of your leaf types so you know how to position it. Put a match or a lighter to various parts of it, flat and tubed and folded.
Well, as I've mentioned elsewhere, when I fill a mold I fill it with 10 different blends (sometimes bunched over several days, to keep things casual), tracked in a spreadsheet. And as I own about 30 different "leafs...."
My hunch is that you can fuck up more good leaf than you can "fix" bad leaf by spraying shit on it. That hunch comes from three years of experimentation, but, you know, grain of salt.