Hmm, Hmm, well, a few things, you should calabrate about every 3 sessions, but I don't, I found that it is usually with in about 2 of calabrated numbers, but you have to get to know your pen. We don't touch the tip with our fingers , but we do wipe ours down after useing each time for the most part. Some people calabrate theirs every other session, but it is really up to you. Just get to know your particular pen and it will start to be easy for you, give it a week or two and you'll have know questions IMO.
Adieu