The current two best squash players in the world (Nick Matthew will overtake the #1 spot in June from Ramy Ashour, congrats to Nick) have by far also the most efficient lobs and drops on the tour. The drop, you can basically play it from anywhere and almost anytime (admitted that you are well balanced and the ball is not behind you). Of course your drops quality will hugely depend on your overall skill- and physical strength-level. Nick Matthew, for example, doesn't have naturally the most extraordinary touch, but he still plays the drop so well, because his exceptionally strong legs and hips give him a perfect balance even on the run. The two most typical situations to play the drop are: 1) after a loose shot, you are on the 'T', your opponent is stuck behind you, you fake the drive and you hit the drop, 2) as a reaction shot to a high paced shot as a volley drop. On the other hand, the lob is generally played when you're in trouble in the front (after a good drop or boast). When you have more time to get to the short ball, which though is tight on the wall (let's say after a good two-wall boast from your opponent), you might want to deceive a counter-drop, and then still play the lob. If I've counted well there are 6 drops and 4 lobs (not counting the high tight lob-kind drives from the back) in the one minute rally below. On top level it appears you have almost as much lobs and drops as drives. Whereas on club-level they are rather secondary to the bang-bang shots from the back.
