Have you ever admired a friend or coworker's lashes so much so that you go to that same salon and get them done yourself only to have them look nothing like what you expected? You're not alone, and it's because everyone's lashes are unique as the individual. Just like hair, your lashes can be thin or coarse in shape, have a longer or shorter lifecycle meaning they will last a longer or shorter amount of time, the natural shape can be anywhere from curled to downward facing and lashes thin with age so while you may of had lots of lashes at one time your lash line may be thinning now.
A classic set of lashes is defined as one extension per natural lash that is mature enough to be lashed, so a person with 20 - 30 more lashes per eye will have a fuller look than someone that has less lashes.