Author here. That's a very good comment. Thank you.
With regards to task queues not being FIFO, they aren't indeed. However, even when you don't have a FIFO queue, a long queue with shifting priorities will cause cycle-times to become even more unpredictable as you'll be reshuffling the queue with time.
You should definitely reshuffle and ruthlessly prioritise, but you should also "tail drop" old items and try to create new ones "just in time".
Which reminds me of the old engineering trick of saying it will take longer than it does as managing expectations is an art best explained by Scotty - https://www.youtube.com/watch?v=8xRqXYsksFg
Thanks for the thought-provoking article. I think I agree with the conclusions even if the analogy isn't perfect. The connotations of under-utilization or over-provision are often negative - particularly in management - but I think as you point out are necessary in order to provide any sort of quality of service.
Qualitatively/subjectively, when I think about the times I've worked as an engineer in an "always busy" environment, I believe that I was often less productive - it's like you need space to breathe. It was certainly less rewarding as it was never possible to be as responsive as you'd like to requests.
With regards to task queues not being FIFO, they aren't indeed. However, even when you don't have a FIFO queue, a long queue with shifting priorities will cause cycle-times to become even more unpredictable as you'll be reshuffling the queue with time.
You should definitely reshuffle and ruthlessly prioritise, but you should also "tail drop" old items and try to create new ones "just in time".