You can also have a look at the attenuation that your yeast has. For example, the yeast I've used is 74-78% according to Whitelabs. I started at 1.048 and I'm down to 1.012, that's 74.2%, so I know that if it doesn't drop more by tomorrow, I've probably maxed out the yeast as good as I can. I didn't add yeast nutrition, I don't have a O2 tube that I can aerate with etc, I just shook the FV which aerates like 30% tops, so I'd be happy with 74-75%.
The reason a lot of people leave their beer in the FV for a longer time (2-3w) is that the yeast gets time to clean up after itself. Not something I'd want my wheat beer to do for a longer period of time
If I'm completely mistaking, someone correct me!