Oh wow, thank you, all of these corrections are extremely helpful. With the 'Fortschritte machen, macht Fortschritt' I was trying to make use of the way we use 'Fortschritte' with machen, but otherwise it's 'der Fortschritt', not 'die Fortschritte'. Or, do I have this wrong?
I can definitely appreciate my sentence is never going to catch on as a new Sprichwort, and it will esp. not overtake 'Übung macht den Meister' ! :D I was just playing with the language.

Both is possible.
From my point of view, we tend to use the singular form when looking at the big picture. "Der Fortschritt" often refers to industrial, technological, scientific, political etc. progress; e.g. "Das ist ein großer Fortschritt in der medizinischen Forschung und Entwicklung."
On a smaller scale we generally use "Fortschritte"; e.g. "Im Vergleich zum letzten Jahr hast du große Fortschritte gemacht." or "Wenn du weiter so fleißig lernst, wirst du schnell Fortschritte machen."
You could picture it this way: The development of a rocket takes us ONE STEP closer to space travel, but someone who learns e.g. a language has to take MANY STEPS on their journey to perfection.