Setting a budget as a whole has many different elements involved. Determining income, determining necessary outgo, and determining what necessary really means all come into play. There are also savings, long-term investments, and depreciation to consider. All of these things play a factor, so it is necessary for each person to evaluate carefully to make their own determinations.
When a couple meets, and falls in love, at some point before cohabitating the discussion of money is a crucial one. In most cases, one person becomes the "banker" and the other person just lives within the predetermined budget. Most of the people I know have a "money handler" in the marriage, and each partner usually complains on some level of the other person's spending habits. It is incredibly rare, in my opinion, that two people agree about money entirely. How ironic it is, that when two people marry, that finances must be shared. Perhaps this is how we learn new ideas about money, and how we redefine our own ideas.
As often is the case, life has a certain ebb and flow, and circumstances change. With every change in circumstance comes a change in your financial outlook. But many of us move along the same path, not taking the time or devoting the necessary attention to redetermining a budget. Often times, it happens when it is too late.
Keep in mind that anytime is a good time to reevaluate your financial situation, make determinations based on your present circumstances and long term goals, and make adjustments accordingly. When you reassess, you have a better idea of where money is being spent and where money is being wasted. Take the time to look at your situation today, and save the money.
Save money and go on vacation :)