The only time I generally take gravity readings is just before pitching and when I'm ready to bottle or keg. For anything but a really big beer, or a new yeast, I rely on my tried and true methods and get the results I expect (better than expected attenuation excepted). I have always, however, ferment in better bottles or glass and can see what's going on from start to finish.
Once you get your equipment and process dialed in results become very predictable. Once you monitor a few batches you'll learn to spot most all oddities pretty quickly.
Bob