I'll quote this (again):
If they complain about amounts, tell them to complain to me. It's best if sources try to exhaust their source allocations, even if it means giving posts higher amounts than is typical. If you have 150 source merit and you only see 3 merit-worthy posts in a month, then I'd rather you over-give each of them 50 merit than let the merit expire. That way there are more people capable of sending merit, and the "merit economy" is less top-down.
I don't really agree though, and wouldn't just dump 50 Merit per post, so I'll leave it up to the reader how to interpret this.
After my last source increase (in January), I still managed to empty it by sending 1 Merit per post most of the time. My stats
last Friday:
5. 6932 Merit sent by LoyceV (#459836) to 1362 unique users in 4744 transactions
But I couldn't keep up that way so my new system was to give more per post once remaining source amount reached 5-10% of the maximum.
Note that once your source amount is adjusted, you receive the total amount instantly. That means no refills for the coming 30 days.
My advice to Merit sources: spend it evenly the coming 30 days, and aim to empty your source around the last day (December 13), so that it comes back evenly after that. That prevents this repeating pattern of running out of source Merits:
I can see from your (micgoossens') sMerit distribution that for months in a row you're out of sMerit before the end of the month:
After this first month, you can keep your source as close to zero as possible all the time to maximize the amount you can send.