Well, I haven't been keeping super-tight numbers, but my village's drain rate has remained about the same with three crossroad posts and an idol. Crossroad posts don't seem to have a large effect on it, but it's possible there's some. The charterstone I honestly have no idea about.
It'd probably be quickest to bug loftar to post about the specifics. We can't really reverse engineer anything since she doesn't know when the idol actually hit 0. It is worth noting that the idol alone is about 54k LP gained with full change (ed: and 10 CHA/INT), and
if she was logged out for about 8 hours and
if it hit zero shortly before she logged in, that's a drain of nearly 1000 per hour, at least.'
EDIT IN RESPONSE TO ABOVE EDIT:
Actually, if she gets decent INT and CHA it's not so bad.
If I understand the math, and you're talking to a guy who barely passed Calculus, so take it with a grain of salt, having 20 (in each) essentially doubles the authority gained, 30 (in each) triples the authority gained, so on and so forth. Having them mismatched really screws with the numbers. So having her switch to Civilization and equipping herself in gaudy +INT and +CHA gear will help a lot.
Also, for reference,
loftar explains it for me here.