Yes it comes from a hand-made spreadsheet. My website has no third party tracking widgets at all: I value the privacy of visitors.
Some time back, I decided that if I was going to keep this venerable website around, I should be more active with updates. That means regularly adding new content and journal entries. As the chart shows, that's good for two things: 1) driving an overall increase in traffic of nearly 50% and 2) reducing the reliance on hits to a 1999 post on my grandfather's funeral speech, which is major Google fodder for some reason.
I've also been looking at the time of day that the traffic comes in. Unsurprisingly, it's bi-modal: traffic pours in during the work day (with a noticeable divot at noon) then picks up again in the evening. I've got a regular tweet feed (through MailChimp) that goes out at 17:00, and sure enough, there's an uptick in traffic at five. But that's when people in my time zone are going home. So I'm moving my tweet feed to two. This will land me in the middle of the afternoon rush for the east coast, and the pre-noon spike for the west coast.
And yes, this journal entry shall be that first 14:00 auto-tweet.