So I track all the XP my group earns in a document on my laptop, I know what they earned it for and when. And I was looking over their XP and realised they were maybe two sessions away from level 2, whereas they only have about one session worth of content left to go on the first floor.
So, no big deal, I went back and upped the XP they earned for searching areas by about 5–10 each. Because there are six I had been bumping up encounter creatures' HP and lowering XP gained from searching areas. But I'm thinking maybe I don't need to lower the CP from searching after all, because now they're roughly one session away from level 2.
The logic behind lowering the XP for searching and the like is that the party can do more with more people, but only one or two characters are really searching for loot and we've had at least one session without anyone searching at all. I might lower it if their behaviour changes in the future.