Trial and Error Based Gameplay

[Koh]

A boss's attack pattern is not the same as a QTE, to even consider that point is laughable. Enemy movement and boss movement ALMOST ALWAYS has a pattern behind it; it's less rewarding(and exponentially more frustrating) if enemy/boss movements are entirely random: THAT is unfair design. QTE's are more to build a sort of "involved suspense" during moments of a cutscene or other "feeling" moment, they only require the basic instinct of button pressing when prompted. Memorization stages require you to use what you have learned about the interaction with the game in order to test your proficiency in that interaction, or to sharpen those skills, that's what the "challenge" of a game is.

You misunderstood my use of the word random. The attacks themselves have patterns, but their ordering does not have to. The boss can do one of the following
A: Dash across the screen, causing damage to the player if the player is in its path.
B: Jump over the player and do a ground pound attack, which damages the player if they're caught under it.
C: Fire a zigzag lazer that burns the player on contact.

Each of them would have some sort of visual cue that they're about to happen. But they don't have to have any specific order to them. If they're always in the same order every time, it just becomes a memorize and regurgitate game, like Puggsoy mentioned, Simon, or like Quick Time Events, where it's the same button every time, only the next time you now know the button order. However, if they're randomized, it puts the player's ability to perceive from the visual cues, and their ability to adapt to a random yet controlled event, which requires more skill than simply replaying it over and over to memorize when and where the boss will be, and create the perfect run.



That reminds me, this is a good read that goes hand in hand with this thread, specifically the Live and Learn section.  For the lazy, a copy paste version is below.

Live and learn

As a rule, adventure games should be able to be played from beginning to end without "dying" or saving the game if the player is very careful and very observant.  It is bad design to put puzzles and situations into a game that require a player to die in order to learn what not to do next time.  This is not to say that all death situations should be designed out.  Danger is inherent in drama, but danger should be survivable if the player is clever.
As an exercise, take one complete path through a story game and then tell it to someone else, as if it were a standard story.  If you find places where the main character could not have known a piece of information that was used (the character who learned it died in a previous game), then there is a hole in the plot.

He talks about other aspects of game design there, but this touches on what amounts to the general consensus of bad trial and error.