So let's talk about PoE (the activity, not the livestream) (Destiny)

by Cody Miller , Music of the Spheres - Never Forgot, Wednesday, May 06, 2015, 22:24 (3733 days ago) @ CruelLEGACEY

The thing that makes the Raids (and even the strikes to a lesser degree) so much fun to replay over and over is that they are predictable enough to allow iteration and improvement from the player. The raids don't change, but the players do every single time, as we learn new tricks, new fireteam formations, new strategies and weapon combos. If an encounter is randomized, the players can't learn from their previous attempts in any substantial way. Every single round is just "GAAHHH SHOOT ALL THE THINGS!!!". And that's totally cool for what it is... I just don't see it as the infinite fun generator that others seem to :)

I think you need to find a balance. If everything is exactly the same every time, then it's just memorization. At that point you're not really playing the game, but just performing rote button presses. There is something to be said about unpredictable situations arising, and having the players handle that.

Basically, an encounter should be designed enough so that overall it is predictable, yet have enough room for smaller unpredictable elements.