Paste this in the JS console when looking at github commit history

see-commit-durations.js

dateEls = [...document.querySelectorAll('relative-time')]
dates = dateEls.map(it => new Date(it.attributes['datetime'].textContent));
durations = [];
for (const [i, dt] of dates.entries()) {
  const hours = Math.round((dates[i] - dates[i + 1]) / 3600e2) / 10;
  const newNode = document.createTextNode("- took hours " + hours);
  dateEls[i].parentNode.appendChild(newNode);
  durations.push(hours)
}