It depends on the complexity of the object, how many details there are, shiny/reflective surfaces = bad, unicolor surfaces = bad, repetitive surface patterns are also bad…
But it also depends on your camera.
lowest ISO possible to avoid noise, Semi-high F-stop for good depth of field, more mpixel = fewer photos needed, better detail, …
Here is an example of an object that gives you full alignment and a complete 3d model (top, bottom) in just 36 photos:
https://dl.dropboxusercontent.com/u/25588164/Chest.zip
It works because there is a lot of features for RC to latch on to and align the cameras.