Or at least warn me when you change it.
My teacher assigned me the exercise in the Friou book on page 81, which is notated in 3/4. I could not make heads nor tails of it. It struck me as a random concatenation of notes somewhat like bebop, where it sounds as if someone had a mouthful of 16th notes and sneezed into a trumpet.
Then, I decided to put it in MuseScore and listen to it until it made sense to me.
That’s when I realized that there are four measures in the middle of it that are basically in 4/4.
So I stuck the new time signature over those measures, and now I can make sense of the thing, and look forward to practicing it. Doing that even got rid of some ridiculous cross-measure ties that made no sense to me.
I kept trying to count it as a waltz in my head while playing it, and those four measures just aren’t a waltz.
Here’s the PDF for those who are curious: Friou Exercise pg81