sidetracking still
That's why I recently started to keep a tennis log with
a) player scouting reports, and
b) match reports....
c) practice session goals & assessment.
I find it's really useful to practice different strategies, even you practice against the same player all the time. Serve-and-volley is usually low percentage play against my current regular hitting partner, who is an excellent returner who likes to stand on top of the baseline. But I like to do it against him sometimes, because if I never practice it, that skill won't be ready enough when I need it against a different player where it is a good option.
Also, I usually play sets in practice. But the tennis scoring system, with only 4 points needed to win a game, encourages conservative play. If I make one error, then I'm in a hole and my chance of winning the game went down a lot. I like to also play baseline games to 11 sometimes. I find that I tend to play a more aggressive riskier style in these games simply due to the scoring. With 11 points needed to win, a single lost point is not nearly as big a deal. There's plenty of time to come back. So this way I can practice hitting a little harder than I usually do. And even if I lose, the psychological effect of losing a game to 11 is not nearly as deflating as getting beat 6-2 by my regular hitting partner (who I'm usually slightly better than) had I played overly aggressively and lost a set quickly.
Hitting harder than I usually do in pratice at times pays off later against certain players because I will need to be able to execute my shots with more velocity than my usual safe style.