Depends on how dirty stuff is really? My ultrasonic cleaner gets used regularly and apart from the very first clean, i.e. to remove engineering oil etc I always run mine for 460 seconds and then just take everything out and dry it. I do use the basket thing, Lord knows why, but I do.
O Rings? I leave them all in place. I have even run a deck with coils through it and heavens, how clean were they then?