Unbound Cultivation or Caster Cultivation

Beings that focus on external energy use will keep their energy unbound from their bodies, allowing them to shape the energy that they expel from their energy pools. These cultivators usually fall under the mage, wizard, sorcerer, witch, and other casting archetypes from games and media pre-flash.
While having the cultivators energies unbound can increase efficiency of external energy use, it is also the default cultivation method when people start the tutorial. As this is the case, unbound is also the usual cultivation of the crafters and other noncombatants, as well as the people who are indecisive. As this is the case, unbound cultivation is the most common cultivation type. 
Unbound cultivation makes it easier to perform external energy use as the unbound energy flows as easily through the body as it does through the air. This makes internal skills much harder to master for unbound individuals, as they have to focus intently to make their energy form the proper patterns inside the body to perform body enhancement skills without leaking the pattern outside the body and causing the skill to fail.

Applied Restriction

As the default cultivation system, it allows internal and external use of energy, but internal use of energy is much more difficult than the forms of energy binding, as it is easy for the user to "stray outside the lines" when forming the patterns necessary to perform internal skills, which causes the skills to fail and rebound, causing discomfort and pain.