your ballad having 4min 30sec is your gears fault, what that means is your casting your songs in a incorrect order. if you lock out songs from overwriting each other, those songs that need to be casted in a order (Or out of order due to mobs dispeling your party and your not sure whats left or everyone has something different on at the time) won't land correctly, infact, you might think you've casted all 3 songs of ballad on someone and you've only got one to land because of the failure to land because of a higher teir blocking a lower teir

The duration for ALL party based songs are the same (2 minutes). both duration gear and song+1 equipment extend song duration. pretty much what you've done is replaced one of your song duration or song+1 equips with a ballad +1 or it could be your ranged equip third/fouth song doesn't match your 1st/2nd ranged equip.
Gjallarhorn and daurdabla have a slightly different duration count since gjalla is 40% duration increase when its song+4 and daurad is 30% duration increase.

This is entirely you being lazy and not changing your casting order.