Yes, I know what you're saying, but the tempo of a song can be altered to suit the horse. (unless it makes the song obnoxiously slow or fast, then go with a better music selection). I realize the music needs to improve the horse's movements, not hinder. That's why I ask if there is a need for this. In most cases (aside from GP level) the music is pretty bad in the freestyles
I've heard enough freestyles that play the entire song as it was written, even if it didn't fit many parts of the pattern. Also, alot of riders leave vocals in which seems odd and distracting
Extending tracks until the horse reaches the end of the vertical (for instance) wouldn't really work, so the change needs to come at the end of the veritical or even at C or A if there's a change to pattern at that point.
What I'm saying is that it's not too difficult to mix various pieces of music to fit the different transitions. You can always compose or mix in a separate piece (a fill) to connect 2 pieces of music. There is software that will nail all of this down. Most time signatures will be either 4/4 time for the walk and trot and 3/4 time for the canter. These signatures work well together. Passage and piaffe could also be done in 4/4, but 2/4 or 2/2 might really bring it out
Thanks again for the information!