After I had finished my flight license, I sometimes neglected to complete a checklist even when I knew the entire checklist back to front. It was usually when I was under pressure for other reasons, for example when I was running late. This also sometimes happened if one of the individual checks took longer than usual. It was easy to become distracted.
I picked up this issue in my reviews and added some assertions to counter this behavior. The key one was “I consciously start and finish each checklist.” Now when I start a checklist I briefly focus on the last item. As I finish the checklist I “destroy” the last item. This reminds me I’ve finished the list.