came out spotless in 12 minutes with no scraping" sounds great but you got lucky with that valve. Ultrasonic tanks can chew up soft metals and dull the edges on brass or aluminum if you leave them in too long, and the cheap ones don't always hold a steady frequency so you get hot spots that pit the surface. That $80 unit might read fine on day one, but the transducers on the budget models die after a year or two and then you're back to the wire brush with a paperweight on your bench. For every one guy who swears by it there's another who trashed a batch of parts because he trusted the timer.

Salting before the boil is the move, same thing happens with blanching veggies, the salt gets into the cells while they cook. Your mileage may vary, but once you do it right, you can't go back to shaking it on top at the end.

File them down and it's a different tool entirely.