I don't think you have to practice aperggios and scales ALL the time but I think you should if you're a beginner.
Ballades are the marathon
At, what, 8-12 minutes each, they seem a little short for a marathon.
But if someone finds it enjoyable to practice such things for no special reason, then why not
For me scales and arpeggios helped me a sh*t-tons with touch and improvising...I also feel much more comfortable when I touch a piano. It may not have been useful to you but it helped me a lot.
I don't know how far advanced you are already.
Thanks all for comments,I recorded myself playing Enya just now to demonstrate, if it's of any demonstrable value I certainly haven't perfected it, and can be guilty of rushing sometimes..I spoke to my teach about grades, and I decided that the very idea of preparing for an exam was stressful to me. I decided that as a compromise it was time I add a more structured approach when practicing, I will start with scales.She also said that I'd not have a problem with sight reading grade I.