I have this same problem, but in a slightly different arena. My ABF does most of his drinking away from the home. So my counting obsession.. I always document what time he came home.
It seems to me like some sort of validation (like what you were talking about) that yes, her really is gone all the time, yes he doesn't associate with me when he gets home. Like one day I'll see some overwhelming number there making it ok for me to leave. Last time I counted them all it was something like 25/35 days he was home past 10pm. I've still been keeping track, but haven't totaled in a while.
I too keep telling myself to stop. What difference does it make, it won't change anything. Yet I keep on. I've also started documenting fights that REALLY bother me. Not just the little ones. I thought they were kind of far in between.. but was amazed to see that the last bad ones were 3 in one month. Might not seem like a tremendous number. But it certainly takes more than a week or two to get over one of these puppies, before having to deal with another one.
I see my day coming, yet I always second guess it. The real timer will begin in 4 days when our second child enters the world. I almost can't wait to see what happens.