It doesn't 'defeat' the purpose if you do it right.
If your maps change BGM by default no eventing you're gonna do will make the music work smoothly for you.
If you walked onto a map that is set to play daytime music when you're walking around it at nighttime you WILL hear the daytime music play, and any event you may have set up to change the music will not kick in until the damage is already done.
So I'm gonna quote myself and explain better.
QUOTE (diamondandplatinum3 @ Jul 30 2012, 11:29 PM)
Set all your maps to never change the music
~ By doing this, your music is NEVER changed when you transfer maps, so your music will remain the same EVERYWHERE (except battles of course) until you tell it to change via an event call.If you've set-up your parallel process which changes music correctly, that should solve your entire issue
. ~ No switches, no anything new, if you've already set it up correctly, you have no issues except maps forcefully changing your BGM.You can use common sense for any maps which don't play music on their own
~ pure and simple, if maps aren't changing music anymore, you need an event to do it for you; intro map would need an event to play the map music, that volcano map that isn't affected by day and night BGM would be fine having its BGM changed in the map data, etc, etc.