Sassie is a platform that schedulers use to assign shops. There are a number of varying ways the scheduler can set up the shops she is sending out (self assign, apply, sent to only men, sent to only people in Florida etc). It really has more to do so with the preference of the the client and their needs.
As far as self assign or apply sometimes the requirements are such that any shopper can take the shop ,other times the scheduler needs to consider more variables so she requires the shoppers to apply
Liz