[SirMaster]

Everyone that I have heard from who uses one say that it reduces the monotonous mental load and frees up their brain to focus more on being aware of other drivers and what's happening on the road, rather than worrying about their speed and exact steering.

People report being more alert and more aware of things about to go wrong.

[thunfischtoast]

I've made a similar experience. Not having to focus on my exact speed all the time (using adaptive cruise control) enables me to watch the mirrors more. It also enables me to keep my attention over multiple hours.

On a kinda unrelated note: I lately see more and more people watching streams or Tik Tok while driving. If of course you use your newly acquired freedom for that it will lead to more accidents.

[literalAardvark]

One thing I really appreciate about cruise control is that my foot can be floating above the brake at all times.

This cuts an entire second off of brake times in motorcycling, where it's just a quick hand move that you MUST do (well, 80% of it, the throttle release part) anyway because if you leave the throttle on you will wipe out, so I'd assume it cuts even more for a move like a large lateral move of a leg in a car.

Only issue is that you need to be careful with that foot to avoid keeping your brake lights on at all times.

Note that this might only apply to driving stick. I'm not sure if left foot on brakes is best practice in automatics.