Your trowel type and size should be whatever gives you the necessary coverage on the back of each tile while providing a minimum of 3/32nds" mortar thickness after the tiles are set.
If your substrate is suitably flat and your tiles are suitably flat, there is no need for an excessively large notch size.
Keep in mind that 80 percent coverage is the absolute minimum
and you really want to get as close to 100 percent as possible. And you always want good coverage on all edges and corners.
My opinion; worth price charged.