I don't think some Yorkies have more Hair than others, all Yorkies are Hairy the only difference is the texture and thickness of their Hair and the rate that their Hair grows? Which depends on Genetics/Breeding and their Diet.
As I retired Breeder and self-taught Groomer (Yorkies Only) I usually start plucking/shaving their Ears around 6 weeks old so they will get used to the touch & feeling/sound of being "Groomed". It's best to pluck quickly and shave both the inside and outside of their Ears at least 3/4 b/c 1/3 off the tip is still not enough, the Hair weighs the Ear down in a Puppy. They also can get Yeast Infections from Bathing if you don't dry their Ears out. The Ears will also look smaller and help them stand erect w/c makes them look more expressive or curious/cute!
