Adventuring XP is a wonderful mechanic. As someone who easily gets distracted by RP, and doesn't always get around to doing 3 writs a day, I absolutely love it, because it's still a very steady trickle of experience. I've even gotten entire levels, just from that stockpile.
HOWEVER, I think the system could do with some tweaks, namely in how fast it can be turned into tangible experience. I understand there's a fine line in there, because you obviously don't want the person who hangs around doing nothing BUT RP to feel like they're levelling faster than people going out and grinding out those levels, however, after one particular writ (Sacking the City of the Formians) delivered a healthy 20k adventuring xp to my pool, I took a step back and realized, that between steady potion crafting, the occasional big writ with friends, and numerous additional sources, I'd accumulated almost 80k adventuring xp, and I don't even have adventure mode turned on, meaning normal mob kills aren't contributing to that number.
As it stands, that pool is going down at a steady rate of 110 xp per Game Tick for me, which means 182 game ticks at this rate will cash in the adventuring exp from a singular writ. That is 1092 minutes, or EIGHTEEN HOURS of playtime, to go through a single writ's experience reward (18 hours and 12 minutes if you want specifics).
It reaches a point where I often find myself destroying my writ charter and flip-flopping between the two writ types, due to how easy it is to hit that 100k cap.
I would recommend a means to "cash in" that adventure pool through other means, even if not directly into experience.
Potential examples might include an NPC who takes from that pool, to give you a (temporary) token that reduces your ECL, meaning more immediate experience from killing enemies for a period.