[mike_hearn]

It's more than that. You can measure salaries too, measurement isn't the issue.

The problem is that if you let people spend the companies money without any checks or balances they'll just blow through unlimited amounts of it. That's why companies always have lots of procedures and policies around expense reporting. There's no upper limit to how much money developers will spend on cloud hardware given the chance, as the example above of casually running a test 10,000 times in parallel demonstrates nicely.

CI doesn't require you to fill out an expense report every time you run a PR thank goodness, but there still has to be a way to limit financial liability. Usually companies do start out by doubling cluster sizes a few times, but each time it buys a few months and then the complaints return. After a few rounds of this managers realize that demand is unlimited and start pushing back on always increasing the budget. Devs get annoyed and spend an afternoon on optimizations, suddenly times are good again.

The meme on HN is that developer time is always more expensive than machine time, but I've been on both sides of this and seen how the budgets work out. It's often not true, especially if you use clouds like Azure which are overloaded and expensive, or have plenty of junior devs, and/or teams outside the US where salaries are lower. There's often a lot of low hanging fruit in test times so it can make sense to optimize, even so, huge waste is still the order of the day.