Serve patterns should be built backwards from the second ball

Servers plan their first serve locations and then improvise everything after, which is exactly the wrong order.

Ask a player what their serve plan is and you get locations. Wide on the deuce, body on the ad, mix in a T under pressure. Ask what happens next and the answer thins out considerably. That is backwards, because the first serve is only genuinely decisive on a minority of points and the rest of the time it is a setup for a shot the server has not thought about.

The useful planning unit is the pair. Serve plus the shot after it. If you hit wide on the deuce court against a right hander, the return, if it comes back at all, arrives from a wide position, which means the open court is the deuce sideline and the server should already be moving to take that ball on the forehand and put it there. That is not a decision to be made in the moment. It is a pattern, and it can be drilled until the movement starts before the return is struck.

Once you think in pairs, the choice of serve location changes. A serve that produces a slightly worse return but a predictable one is often better than a serve that produces a slightly better return from an unpredictable position. Predictability is what lets you start moving early, and starting early is worth more than the marginal quality of the return you induced.

This is also where second serve strategy stops being about survival. A kick serve to the backhand that produces a floated ball to the middle is a winning pattern if you have rehearsed the forehand that follows, and a losing one if you have not, and the serve itself is identical in both cases. The difference lives entirely in whether the server knows what they are doing next.

I would spend half of all serving practice hitting the second ball. Most players spend approximately none of it, because serving alone into an empty court is convenient and hitting the plus one requires another person.

Convenience has shaped tennis practice more than any coaching theory.

The serve is a question. If you have not planned the answer, you are just asking politely.