Same with pens - my handwriting varies with the nature of the pen, paper, and I suspect, even purpose of writing.
I have recently found myself using pencils a lot more than I used to. (We have purchased so many pencils for CTQ and Thinq2win that the house, bag, and notebooks are infested by them). I think my ineffectiveness with pencils is the least worrisome. It is like humming a tune poorly or dressing badly. Done in the safety of the house, you have nothing to prove and nothing to be ashamed of.