What are the criteria for determining a Shrink Shot?

I am considering starting with Shurink. I've noticed that Shurink shots come in various counts, such as 100, 300, and 600. I am curious about the specific criteria for determining the number of shots. I need to study the basics before going for a lift so I can ask questions during the consultation. I would like to know what concerns you had, how many shots you were given, and how those issues were resolved.