Ron Jones used larger orchestras than McCarthy. He would sometimes use 60 or more musicians on certain episodes. This would of course mean that his scores were more expensive to produce.
Your figures are incorrect. According to the FSM stats
, the largest orchestra Jones ever employed was 59 members, and the overall average was 42 members. (Averages: S1: 38 members; S2: 50; S3: 44; S4: 37.) The numbers were highest in the second season, and in the fourth season he always used orchestras smaller than 40 members except for BOBW Pt. 2. So he was certainly capable of working with smaller, less costly ensembles, particularly given how much he relied on electronics.