This is a continuation of the last post about getting to the kitchen and is more-or-less a summary. The third shot of any rally is when the serving side plays their second shot after serving, the one where they must stay back and allow the ball to bounce before playing it. Assuming the return of serve is deep to the baseline, normally this third shot will be a drop, a fairly soft shot lifted so it apexes before the net and drops down into the opponent’s kitchen. This enables the serving pair to makes some progress to their kitchen.
So the serving side should assume the return of serve will be deep and they will be playing a drop shot. However, sometimes the return of serve falls short of the baseline and may fall half or three quarter court. When this happens the serving side has to move forward to the ball and has the option of a) playing a drop as planned (although easier as they are nearer the net) or driving the ball low over the net at pace. Either way the shorter return of serve means the serving side have been given the momentum to move up.
Driving at the pair at the net from mid court gives then little time to react and control their next shot and may produce a pop up to attack. The reason it is not advisable to drive the third shot from the back of the court is that a good pair at the net with soft hands could just block the ball back into your kitchen. Starting from the back of the court, this will be a difficult shot to get to and control.
In summary, the serving side should be prepared to play their second shot with a drop but look for a short return of serve which they may be able to attack. In any game situation the shot you will play will depend on the merits of the ball you are receiving and your perception of the skill level of your opponents.