Easy Rider. A cent is 1/100 of a Herz (cycle per second). When you listen to beats you are usually listening to about one beat per second--so you can imagine how small a cent is in real terms. All of these temperings are compromises to allow us to play our intsrument in a lot of different keys using the same frets (or keys, etc.). Of these Well tempering is the newest and the best compromise. Unfortunately it requires that every sring is used for only one note (like on the piano) so we can't use it for guitars. Lutiers choose the second best which is equal temprament.
Helen, I think the contraversy as to whether an electronic tuner should be used usually applies to instruments with a few strings--guitars, banjos, violins, etc. where the situation you describe of spending your life tuning doesn't exist. By the way, how do you tune if you are playing with somebody else. What do orchestral harpists do?