I would think that the consequences need to be pretty immediate to have a psychological effect. Seeing at the end of the month, "Wow, I broke the build 8x. I should be more careful." just doesn't carry the same sting as "Oops; there went today's coffee budget!"
Presumably you get an email or other notification when the build fails. So even though the deduction isn't immediate you still get the immediate feedback that you will be deducted.
