Oh yes, the freight line is not a platform. I would of thought Bradford on Avon/ Trowbridge/ Frome/ Bruton/ Castle Cary are better stations for accessing the rural hinterland, as you don't have to walk through much town to get into the countryside. But Westbury is served by more trains than...
Plymouth in rush hour is... Well... It's not a nice station at the best of times... All the subways are too narrow for the volume of people and there aren't enough lifts. Also, all the peak hour services seem to illogically depart from the far platforms, when platform 1 and 3 are empty.
Westbury has only got a population of 15,000 and gets served by 3 or more trains every hour.
However, further down the line at Frome, the population is 26,000 but it only gets served by about 10 trains a day (I think! Please tell me if this is incorrect!)