but if this build is executing multiple charges in a round, would not each separate charge get the separate bonus? just because the situations are identical, the bonus is only applying to one charge at a time... just lots of them.
If the bonus did apply to the charge, would that not merely mean that you have to move that much farther before you can initiate the charge? A charge normally requires 10' of movement, or 5' for Battle Jump. So, if the +5' bonus applied to the charge, Battle Jump would suddenly need 10' of movement to be able to charge, or 15' for a normal charge. Remember, the only part of a charge that lists distance on a charge is how far you must first travel. Therefore, the bonus must strictly apply to the speed, not the charge.
If this bonus vanishes after you have charged, so that you may apply it again to a second charge, then you are still stuck with your speed +5' as the maximum you can move in the round. Once you have moved that much, there is no more available to get you away from your opponent to try another charge, to regain the +5' bonus and thereby get 5' again after you've hit your limit.
If the bonus does not vanish, then it cannot stack with itself, and you are limited to your speed +5' for the round, anyway.