Like everything you will eventually end up with diminishing returns. E.g. I doubt many people track potatoes vs carrots, or underwear vs socks.* But: 1) Once

Like everything you will eventually end up with diminishing returns. E.g. I doubt many people track potatoes vs carrots, or underwear vs socks.* But: 1) Once you've automated most the of the steps, it takes, say, 1h per month to have everything up to date, so basically nothing. 2) Compared to no tracking, you can often end up finding money another party owes you. At that point, the 1h per month is financially worth it. 3) How little can you spend if times are tough? Any theoretical budget will pale in comparison with actual tracking of past expenses. Once you know this, you know how many months of spending you have in cash, meaning you can invest the rest in the long-term. 4) How much will you spend in 5 / 10 / 20 years? Why? You can better estimate this with accounting. 5) Let's say you spend $x on hobby A and $y on activity B. Does that reflect how much you like A and B? If not, maybe change it? *: still... how diminished is your salary if you start a job that requires that you wear a suit everyday? Is it still better than the other offer you rejected? Maybe you made a mistake? This is way