it was mentioned in earlier episodes though that becka performs a lot of other functions as well. In one episode, it was mentioned that only she and Bobby are aware of the firm's financials and cash flows, which indicates that she probably performs a lot of back office functions. Other than that, as a lawyer, Jimmy's character is supposed to be crappy and few have confidence in his ability as a litigator, hence Bobby constantly wanted lindsey to step in when he was working on his power line case. At the end of the day, Becka while a secretary, is intimately familiar with the firm's operations as she and bobby were the first two original employees. Seniority and loyalty does count for something.