Other:
I used adventures as a guideline, but I adapt them as needed to fit my group and campaign. Basically between time saver monster stats and changing only the setting. I regularly change more than just the setting, but I always keep the concept of the adventure intact.
This is similar to me. Where possible, I'll run adventures as-is, purely to save prep time. However, a lot of the time there is a part of the adventure that doesn't fit with my campaign setting, or my players or PC's. Other times I make changes to the adventure based on feedback from other forum posters on EN World or Paizo, replacing some bits, adding in other stuff, taking out stuff that doesn’t work well.
For example, in the adventure “The Encounter at Blackwall Keep” in the Age of Worms AP, the opening encounter with the lizardmen was underwhelming, so I changed a lot of it around to make it more challenging. Secondly, the proposed set-up didn’t make a lot of sense (the party is travelling with a high level Wizard who teleports away to get help upon encountering the lizardmen, rather than sticking around for a few rounds to drop some fireballs on the lizardmen and help the PC’s), so I completely revised that. There was also plot information in the adventure that the PC’s had almost no chance of being able to find out, so I revised some of the lizardmen’s actions to give the players a chance to find this information out.
Finally, a poster on the Paizo forums came up with a cool way for the players to first come across the Spawn of Kyuss indirectly by having the players take control of some NPC guards for an encounter as they find the Spawn. How well or how badly the players do in that encounter determines just how many Spawn there are in the keep when the PC’s return. The encounter was a great change of pace and the players really enjoyed it.
So while I generally keep the overall plot of the adventure the same, I will often change a lot of the moving parts within the adventure to make it a better experience for my group. Sometimes the changes will be small, other times they will be quite large.