How long it takes to beat Black Myth: Wukong will largely depend on your success with its many, many boss fights. Some levels are more dense with secrets to find than others, but getting stuck on a particularly hard fight will slow your progress down the most. Wukong isn't your typical soulslike, however, and makes it fairly easy to keep moving through its chapters without losing too much time.
Wukong has six chapters to play through and some of them are considerably longer than others. Chapter 3, for example, acts like it's going to end several times before it finally transitions into chapter 4. You also have the option to go back to previous areas and look for items or upgrades you missed, which can take a while if you haven't unlocked every shrine checkpoint.
Black Myth: Wukong is around 30 hours long, give or take some time if you're a very thorough explorer or get stuck on an obscure sidequest. The hour count could easily climb to 40 if you want to squeeze everything out of the game and as low as 20 if you rush through it. That means each chapter should take you around four to six hours.
As I got comfortable with the pace of Wukong's combat, I sped through its areas, rarely dying to normal enemies. Here and there a boss would give me trouble, but what could've taken hours of attempts in other soulslikes, only took an hour or two max in Wukong. If anything, my terrible sense of direction cost me more time than the bosses.
Here are all the chapters and their associated areas that you'll need to play through to finish the game:
There are a handful of secret areas in the game, like one that opens up after ringing bells in the first chapter. They're generally fairly small, but can be a pain to find if you're not combing through every area for hints.
