My piano teacher holds recitals twice a year, and generally each person would perform two pieces. For my part, I gravitate towards pieces that are unlikely to have been played at previous recitals before. I actively avoid pieces along the lines of Minuet in G, Arabesque (I suppose both the Burgmuller and Debussy ones could qualify here), Clair de lune, Moonlight Sonata, Fur Elise, etc. My very first recital, I was one of three people who performed Petzold's Minuet in G major. I performed last among those three people in a recital arranged roughly in order of piano level, and I felt very embarrassed in a situation that amounted to, "nice job with your piece, now here's the same piece but better."
So at least one, usually both pieces, will be own choice. I like to collect piano solo sheet music both old and new as a hobby, and I actually have boatloads of music at my current level (about ABRSM 4/RCM 5), so a couple of months in advance I'll choose pieces out of whatever I'm currently learning. I use syllabi as a guide, but I avoid pieces that are in the exam books themselves. My teacher will have also recommended pieces to me throughout my lessons, of course, and I might pick one of those for a recital, but not if it's well-trodden ground.
