It depends on what type of ultrasonic cleaner you are using. You’re average jewelry ultrasonic cleaner won’t do diddly squat for coins and relics. You need an ultrasonic cleaner with a true sweep function and degas feature, which used to start in the $300-$500 range but some companies are now producing some that are in the $100-$200 range.
I use an industrial ultrasonic that I had from when I was repairing water damaged rusted out cell phone’s doing data recovery. On relics it will make a night and day difference. I’m about ready to run a cycle on some toasted civil war buttons I pulled, and you’ll see the difference. For coins I only use it on clad, though I have used it on old tokens to pull details.
As a side benefit to having an industrial ultrasonic, you no longer have to worry about cleaning your gun parts after a range day. No matter how choked up with carbon they are, you just drop in for a couple minutes and out pops brand new looking gun parts.
Most in the metal Detecting community aren’t familiar with ultrasonic cleaners beyond your average single frequency store bought jewelry model, hence you’ll get mostly incorrect info on the topic. I can point you to some ultrasonic communities if you’re interested in it more.