Wow, super cool to see new metrics like that. I don’t have numbers for it but another tip: if you find yourself very productive at a coffee house or library, often it’s the chair and desk they set up. Sometimes if it’s good enough, you can just note down the brand and buy your own. Copy the ergonomics.
Also considering a CGM for a month and weaning off of caffeine. Trying to reduce days were I feel like I'm dragging.
I did this once and found a cool custom furniture hack. Asked coffee shop owner who made their tables, and he referred me to a local woodworker. Called the woodworker and asked for the same table. He tacked my order onto a bulk order he was working on. Got a custom handmade ergonomic desk for 50% less than Ikea.
Very missable detail but I have noticed that the table height while sitting makes a world of difference. A few inches up and down just changes the entire mood / flow.