I am from Australia. I have been teaching for more than 30 years, the ones that only do exams are the ones cannot play anything once all exams are done. Get your students to learn enjoyable music that will boost up their sight reading, but also coach your students to perform at concerts, enter music competition etc. Build their confidence and enjoyment of piano playing, that last for life.
Just as learning swimming for safety and health sake, so as piano learning is for leisure and entertaining people with good music, that's a musician should be. My students do a lot of performing and competitions, not all are keen to put up with the same pieces for so long just
for the exam sake which is so boring and lacking motivation. Once they have confidence in performing, taking exams would be less stressful.