“Don’t think too much about your game. As long as you keep playing, you will improve.”
Get sucked into this advice too much and you will reach an unclimbable wall. This advice is only valid up to an extent. Practice and hard work is absolutely necessary to be a good player, as it builds muscle memory, reinforces your current habits, and strengthens your tennis IQ.
However, there is a ceiling to how good of a player you can be depending on the strength of your core fundamentals – technique, footwork, strategy, mentality, and physicality.
It is true that most people never reach this ceiling due to lack of rigorous training. Those that do will notice their progress gradually slow down as they get closer to it. Practice allows you to achieve logarithmic growth; you will improve seemingly linearly, but your growth will slow down as you reach the top.
Whether you believe you are near this ceiling or not, improving your core fundamentals is what will lead you to exponential improvement. Lacking essential fundamentals can place limitations on your game, while having strong fundamentals can remove these restrictions and allow you practice towards your full potential.
Many coaches argue that there are a variety of styles which develop from having different fundamentals, and athletes have been successful with their playstyle. Therefore, there is no need to improve your technique or footwork or any other fundamentals.
The problem is if coaches have this mindset, they are reducing their responsibilities, as this claim implies any coaching advice does not help towards your improvement. Although it is true that professional tennis players have differing game styles, all of them share certain aspects of modern tennis theory that closely model each other. Compare their fundamentals to amateur tennis players, and it is the most obvious.