Well looking to see if you are being cheated is part of it. But only a small part. Spreading your play around 30 casinos, plus some out of town play, you aren't going to come close to having a large enough sample size at any one place to definitively prove anything about cheating. Not in any single year. Maybe over a number of years.
But really the reason I keep detailed record is because I want to know just how far below or above expectation I am running for the year. Especially as you get towards the end of the year with a larger sample size. And no it doesn't change anything, but I just like to know.
Not currently, but most of my first dozen years in Vegas, most years by years end were pretty close to expectation. I played 80-100 thousand rounds a year and that was enough that most years were pretty close. But even more than that if you expand out a little and take results for any 2 or 3 year period and compare to expectation, it was amazingly close.
And while that doesn't change anything, it is just sort of confirmation, or re-affirmation, that the math work. Even 20+ years in, there are times I go on a pretty good losing period for weeks and months, and despite 20+ years of doing this, You start to say what the fuck!!?? Then I look at my longer term numbers and it just sort of re-affirms that everything is working just the way the math says it should. Just a little variance. The math doesn't lie.
So no doesn't change anything, but it helps me.