One more -- and this comes up a lot -- anything where latency or a delay matters. An analog circuit can have response times in the tens or hundreds of picosecon

One more -- and this comes up a lot -- anything where latency or a delay matters. An analog circuit can have response times in the tens or hundreds of picoseconds. A digital PID on something like an FPGA in the nanoseconds. One on a basic microcontroller (the kind without an OS -- PIC, AVR, ESP32, etc.), in the microseconds. An RL algorithm running on a general-purpose computer, you'll be lucky to hit tens of milliseconds. That makes a big difference. For those unfamiliar with control systems, delay matters a lot. Something like an audio amplifier (where you can't hear anything <20kHz) will generally have a bandwidth in the tens of megahertz, and more is better. A rule-of-thumb is: https://en.wikipedia.org/wiki/Gain%E2%80%93bandwidth_product https://en.wikipedia.org/wiki/Gain%E2%80%93bandwidth_product In other words, if you'd like to bring down error by a factor of 10,000, your loop will generally like to be around 10,000x faster than whatever it's controlling. If something has a time constant of 1 second, you still might want to be able to react at the speed of microseconds. That's not a hard-and-fast rule per se (I can give all sorts of ways to work around it), but what is true is the more general principle that minimizing delays can be very, very helpful (even for things which otherwise seem pretty slow).