I usually leave the parts in until they are clean, Time varies. In my experience, heavy grease does not come off well without a prerinse and scrub in kerosine or something similar. I have found that a strong solution of regular simple green and water works well for around three heavy cycles and then seems to lose its potency. It is cheap enough; I just replace it. (but regular simple green is NOT aluminum safe)
I have a couple of cheap ultrasonic cleaners and they are noisy! I leave them in the garage. The high-end ones are tolerable in the house but $$$.
I once left one running that did not have a timer and when I remembered it, the solution was boiling!! I caught it in time, but if it had boiled dry, the least that would have happened would have been a ruined ultrasonic machine, the worst, a burned down house? Even though these are small machines, they are powerful at the chemistry and physics level. Use with care, they can and will ruin things. Keep your fingers out of them when they are running!
The Ball jar works well for small parts, so they do not get lost and are easy to retrieve, and as a hack, if you need to use some type of fluid that is more aggressive… just float the jar in water like a little coracle and Bob’s your uncle.