Singles in hairline

[Cant decide]

I know singles in the first cm of a hairline is standard to create a nice tradition zone. However, the down side is that until you hit the "twos" beyond the 1cm, the hairline can appear thin. Has anyone out there added additional singles to the front 1 cm and did it make a nice density difference? How many did you add?. I am thinking 500 singles may do the trick.