Piano tuning is an art that I was privileged to gain from my father while I was growing up in Australia. Although I use the Tune Lab Pro (TM) computer program in a notebook computer, I rely entirely on my ear for fine tuning. The computer allows me to set the pitch for A440 and can be a great help with the very high and low notes. There are also other great features of this program. However, it is essential to tune by ear for the temperament, unisons and octaves as "what you hear is what you get". The time needed to tune a piano mostly depends on how flat it is from A440. My rule is that a piano more than ten percent flat will require two tunings to produce a satisfactory result. Ten percent flat is defined as the percentage difference from A440 towards the next lower semitone, called "10 cents" by tuners. The first tuning is to roughly get the piano up to pitch. This is called a "pitch raise". A fine tuning is then performed about a week later after the piano has had time to settle in to the new tensions of the strings. Usually a tuning is not stable if a fine tuning is attempted with a piano that is more than 10 cents flat.