I found a physical kitchen timer most helpful. It's really quick to set it and I can chop veggies or wash the dishes in the meantime, without having to check the clock all the time.
You can also get one with a magnetic base and stick it to the fridge.
I'm no expert. I probably know too little about the propagation speed of a wave to understand what you mean there.
But here is a scenario where something is faster than light in the given medium: https://en.wikipedia.org/wiki/Cherenkov_radiation
As I understand, neutrons and gravitational waves are also bound by the speed of causality, because they have no mass. And I believe, unlike light, they are unaffected by electromagnetic forces that a material exerts, so they would presumably (always?) travel faster than light in that medium.
I will also say, that from what little I understand of this video: https://www.pbs.org/video/pbs-space-time-speed-light-not-about-light/...it sounds like trying to determine the speed of causality by measuring it, is kind of backwards. You're at best experimentally confirming what has to be a given under our laws of physics.