The old days of PFM (UGH),I would often see a monochrom opaque without regard to the finished product. then 90% build with dentin and hit the occlusal with some incisal. ... Change the language. Calling it 'incisal' porcelain infers a location. Its enamel, and should cover the entire crown.
Yup, years ago if you went to a hands on porcelain class, they usually would talk about incisals. But user name is right. You go to a Drs seminar and they'll talk about enamel and enamel rods, not incisal or incisal rods.