Always remember, if you don't think your visit quite qualifies as a DNF, you can always log a note. If you get near the site and your batteries die and don't bother looking, or if you get to the parking and you realize it's after hours or it's too far to walk late in the day, or for other reasons like that it's always good to leave a note at minimal for two reasons. Firstly it tells the cache owner people still have an interest in finding the cache, and secondly it gives you a record of when you were there and didn't look.