nobody is arguing the difference between free lance, and contract girls, we are just talking about the hardest workers and how contract girls shouldn't be considered because most release one or two videos a monthIf she's releasing titles from various studios that truly are independent of each other, she may not have an exclusive contract.
Exclusive contract is the equivalent of being a salaried full-time employee (seishiki shaiin): they trade a POSSIBLE slight reduction in monthly income for stability and a set amount of titles to appear in each month. Of course on top of filming, there are promotional events which may or may not be part of the contract.
An AV star with no exclusive contract can work herself crazy by appearing on sets every single day. It's a great way to make a ton of money fast, but there are a whole world of risks involved.