I think the data supports that there were about 5 distinct days when I did a large amount of work on this library, and a sprinkling of minor commits through the rest of the month. Glen's commits, while numerous, were also fairly minor, mostly logistical details around releases.
This library is not the only thing I was working on, nor even the main thing. As the lead engineer of Cloudflare Workers I have quite a few other things demanding my time.