I use the fills on a "as needed" basis, and it's intuitive, NOT planned or reasearched. I learned from my teachers long ago, that most of the energy of any emsomble performance needs to come from WITHIN the sections, and not from the drums. The rhythm is generated from the individual parts intreacting as one to create a groove that has "power" and force.
I DO use the fills, but it's more important to use notes to make transitions. A straight ahead, time keeping drummer is all you REALLY need. The real energy and sizzle comes from the arrangement it self, and how the parts all interact ... including the drummer of course.
Point is:
fills are only as neccisary as the placement of notes that create the accents as well.