Years ago, in the era of leaded gasoline, infant unleaded and stinky catalytic converters, my dad advocated the occasional tank of "hi-test" or premium gas. This did help clean out a carburetor and would often help a car run better. He said it would flush trash out of the fuel line. Perhaps there was something to that. He got 260,000 miles from his 1977 Chevy Nova before it finally died on him.
Nowadays, with fuel injectors, I don't know that messing with the octane level is a good idea. Computers control the cars and are programmed to perform with a particular octane level. I have heard of using a bottle of injector cleaner every so often, to get the "gunk" off the fuel injectors, but I think mechanics are a little leery of advising customers to use an octane level other than what the car is rated for, except in an emergency.