From my music training, I knew that, some Spanish rhythms...

From my music training, I knew that, some Spanish rhythms apart, 5/4 is a time signature used only in the modern era. Holst's Mars from the Planets is 5/4. But if you speak lines of poetry in that pattern you just end up hitting the off-beats. It's only when you add a rest - a sixth beat - that it sounds as it surely should sound.