Best way to have text change during an animation? The short version

I want to create a very simple animation that will change the text of two fields based upon the time elapsed in the animation. I think that the python API is the best place to start, but not entirely sure of that.

I think my question is a duplicate of How can I make dynamic text in an animation?. For my purposes the simple python scripting will work best, but that Animation Node add on looks amazing.

Longer

I want to create a training aid for some musical exercises (Stick Control). Each exercise is played 20 times and generally I'll play 24 total exercises. Depending on the tempo, the total animation will run from 20-50 minutes.

I'll create a metronome track in my audio application and put the two together for the final product.

I intend to do several versions at different tempos, so python was appealing b/c I can put the BPM in the script and then derive what's needed from there.

Hopefully, that's pretty clear. Really looking for the best starting point. It would be really nice if I could get the changing text during the timeline scrub so I could verify that I was doing things correctly without having to dump a complete render each time.

It occurs to me that this is somewhat similar to a walk cycle (on the repetition count), some way to easily change the time scaling for different BPM might make that approach a winner as well.
I don't know exactly how to do it, but if you are looking into scripting methods of doing this, check out animation nodes. This sort of thing is pretty much what it was made for. You can use nodes as well as custom python script to get what you're looking for.