Note that from a statistics point of view shared exp is always worse than training the skill individually.
Person A trains with shared, person B trains individually.
Person A is 1/3rd done to get a level
Person B got an Attack/Str level (DPS increase)
Person A is 2/3rd done to get levels
Person B got a str/atk level (DPS increase)
Person A levels ATK STR and DEF
Person B levels DEF and is now on equal foot with person A