So, I am rereading the past things I did in a book that is for learning piano, it gives you an explanation for something or just something new and then it applies it with some sheet music for some song that you probably don't know. I want to focus on learning how to play by ear and am working on my pitch so I just went through out of boredom and for recapping purposes to give me some pointers I may have forgotten.
Anyway, it used 8va and 15ma at one point (I forgot what the song is called) and I assume that I did as it said and used the breaks to move an octave or two up or down. This made me realise that I always went to the fourth octave for my right hand and a bit of the third and fourth octaves to play at the start of most pieces if I wasn't given a direction to move or start elsewhere. This is probably because of middle c, but still, is this necessary? I get it if you're trying to play a specific song but what if I'm not? What if it's an unknown tune and I'm told to just play it on the spot? My teacher sometimes does this to give me an idea of what my homework is and give me tips on how to work on that piece.
If someone were to play piano using piano sheet music to play, which octave would they start playing the beginning on if the sheet music didn't specify? Would it be up to them if they wanted or would it always have to be the fourth and third octave?