Turboheat requires a minimum of 6 outlets to safely disperse the volume of radiant heat produced.
Turboheat has a maximum of 14 outlets before it is required to be zoned.
It doesn’t take anymore energy or wood to run between 6 or 12 outlets. The heat is already produced. The more dispersion of the heat via the duct outlets the more efficient and comfortable the house will be.
Turboheat does prefer you to run it’s own ducting. However on the odd chance that there isn’t enough space in the roof, or you have a ducted refrigerated system or gas. You can purchase a tap in kit to merge the systems together.