Traditionally I have run mostly homebrew adventures. I’ve used encounters taken from commercial adventures every once in a while. The Dragonlance campaign I’m running is the first I’ve really tried to run a module straight.
My players aren’t always going along with that idea but that’s ok. I’ve also added some content because I wanted a special event for the character with divine powers. I plan to do the same for the knight. Due to this I created Dulsi’s Dragonlance Addendum on DMs Guild.
For Spelljammer I found the process less satisfying. I had to tweak many individual encounters to match what I wanted. So running it requires looking at the adventure and looking my notes for things to override.
I’ve been using the Pathfinder 2E Beginner Box, and it’s the first time I’ve run a premade adventure. I’ve been customizing it quite a bit in terms of the story to better match my players. I expected the adventure to feel stale and on-rails, but what I found was that it gives you a safe baseline to work from. If you find any parts of session planning stressful, you can just leave them at the baseline and devote more of your time toward the things you actually enjoy.
In my case, I was still learning the system, so it was nice not having to worry about balancing encounters, drawing maps, or distributing treasure. Instead, I was able to spent my prep time on modifying the story.