In the past I've opted not to go every 6 months, but try to make it once a year; but me being me it's 12 months then about 3 of, "oh I must get around to it". And generally it was minor stuff or nothing to be done when I did get there. Over the past year or two though I'm not needing to note the date since the last check up because things keep going wrong and I phone for an appointment anyway. Teeth seem to want to move about and no longer line up properly, and they lose bits, are too sensitive, expose gaps to gums, etc.. Take my advice, don't get old.