As SFC Michael D. said, it depends on what the waiver is for. A waiver for promotion could be based upon either depending on what was needed. IE if an E-3 had TIS but did not have TIG then a TIG waiver would be used.
One or both. Also, there is not an unlimited number available to a unit. There is a calculus that goes into determining the number available. We really need more to get you a solid response. Thank you for your service.