It varies somewhat by plant and pot size, and definitely by time of year, but in warm weather the general rule of thumb is most potted plants need to be watered once a day. A really small pot, or one with a large plant, might need to be watered twice on a really hot day especially if it's in direct sun.
Daily watering is usually only necessary once the weather turns warm, before that you have to go by how dry the soil is. In fact the "dry soil" test works any time of year, but during warm or hot weather it will almost always end up telling you to water once a day. The "dry soil" test is to stick your finger into the soil and see if there is any moisture below the surface. Not wet, just enough moisture that it is cool and you can detect a little dampness. For a big pot sample the soil a half inch below the surface, on a small pot closer to the surface.
The other way to check soil moisture very quickly for a light weight pot is by picking up the pot - a pot that is ready to be watered is noticeably lighter than a well watered pot, and a really dry pot (too dry) will be almost featherweight.