Short month = Extra money?

So, for years now we have had a set amount of money that we can spend every week. This money can be spent on groceries, dog food, toiletries, household items, eating out, going out, stocking up on sale items, clothes, shoes, etc, etc, etc. Basically, we only try to spend this set amount of money every week, regardless of what our needs are.

For about 6 months now I've been inconsistently trying to cut this weekly amount by 1/3. But it never happens. We always end up spending exactly what we have budgeted (or maybe a few dollars more, in which case it just comes off the next week's budgeted amount).

Every February, I find myself thinking about going on a "spending hiatus" for a month and only buying things we really, really need. And every February, I never actually do it. This year I thought about it, and thought it would be pretty hard to not stock up on sale items, etc if they are a rock bottom price. So instead, I've decided that I'm going to cut our weekly budget by 2/3 for the month of February only.

My hope is that by setting a goal to only spend 1/3 of the original amount, even if we go over we still won't be spending more than 2/3 of the budget, and either way we end up saving more money this month.

I'll let you know how it all turns out!