Cash spending is often lumpy. You might earn a salary for a month all at once or have to pay a water bill for the whole quarter. This makes it difficult for you to know how you are doing in any particular month or week.
Buckit recommends that you take these transactions and "split" them across the applicable number of weeks. A monthly amount gets split across 4 weeks, a quarterly amount over 12 weeks. This makes it easy for you to assess your spending every week and quickly adjust if you feel like you are getting ahead of yourself in any week.
Sometimes it feels like you might have spent too much either because of a big purchase or a big monthly or even worse quarterly payment. The reality is that this is often prior or future spending. In cases where you buy something that is going to last for several weeks you have prepaid for something in the future. Splitting that spending over the weeks where you really use it makes it easier to understand when you spent that cash.