I have recently trained in Russian Volume Semi-Permanent Eyelash Extensions.  Instead of applying 1 extension to 1 isolated natural lash, I use lighter extensions and make a fan with 2-6 extensions and apply the fan to 1 isolated natural lash all using the same dip of glue.

Because lighter lash extensions are used in volume in can make the lashes look more natural and fluffy, however a much more glam effect can also be created.