A significant aspect of tumbler v vibrator is that the vibrators are generally much more agressive, and therefore time-sensitive, subject, of course, to the type and condition of media.
Due to the variables mentioned above it is difficult to make a definitive statement, but generally, an hour or so in a vibrator is about all you want to go without violating the integrity of the cases, whereas the less agressive tumblers can be run all night long to achieve the same results.
I prefer the Thumlers tumbler on an all-night run, because it is in effect, "instant cleaning" because I can start it B-4 I go to bed, and the brass is pretty the next morning and i don't have to worry about setting a timer to avoid brass deterioration.
I left a load of 9mm range pick-ups (I only have about 50,000, but I still pick them up) in too long, and they were thinned to the point that the rims would pull of in attempting to pull them out of the carbide resizing die.
I tossed them.
The type of polish you use also has something to say about it all. I have used, with some success, non-ammoniac car polishes.
Nickle takes about half the time of brass.
Media that is no longer viable makes fine "sandbags". Put it in a plastic garbage bag (small size) and tie the end and put it in an empty shot bag and get your bride to run the Singer across the end of the bag a few times. The plastic bag keeps the media from soaking up moisture in event of rain.