[throwawayjava]

This comment is a tad ironic. My monthly expenses are $N, and I keep at most $N + 1,000 in my checking account. Often much less e.g during the first half of the month. I keep my checking account balance as low as possible precisely because I know "the difference between checkings and [high-yield] savings". Keeping more than a small buffer extra in your checking account seems pretty financially illiterate to me.

Also, keeping anything more than absolutely necessary in a checking account is ridiculously dangerous if you're using ATMs outside gas stations....