I think what you say is probably true of most platformers and other games like Sekiro (a successor to dark souls which was one of the original non-platformer games like this) but definitely not all games.
It depends on the exact context and goal. To an extent, I would consider "map painting" the equivalent of a speedrun. It's usually measured in elapsed game time rather than play time, but there's a similar effect.
Especially with some of the more difficult OPMs, there can certainly be an element of memorization and optimizing starts. This falls off as the game goes further, but it definitely can be present. I recall some years back reading an EU3 byzantine guide that described many of the nations as being every bit as much puzzle game as strategy, where figuring out the tricks and traps of the opening years can mean the difference between a thriving growth and early defeat.
Not that anyone ever has to play the games that way, but that's true of everything that gets put through a traditional speedrun as well.