Almost none...
Think about it... what's the difference between standing on the left v right? none.
It's just for consistency's sake. If you're used to palpating from the right then you're know what normal will feel like from that perspective. If you then change where you perform your exam so that you started palpating on the left, then you'll be more likely to misinterpret findings because you're not used to feeling things from that side. The same can be said if you were to do most of your exams by standing on the patient's left, and then suddenly stood to their right.