I take half of an adult aspirin every couple of days. Makes my nose bleed, though --some prior damage in there. I sometimes take half of an Aleve instead.
My pill cutter is used a lot.
I'm the same way with most supplements, I rarely take them consistently, but sort of "take one from column A and one from column B" sort of every day, but not necessarily. Some things definitely upset me, like one brand of multiple vits.
When I was taking larger quantities of aspirin, I found it interfered with my integrative mental processes. I thought it was the onset of Alzheimer's at the time but it went away when I cut back.