I think this is just a guideline for people who have no clue to budget to follow, honestly.

Some people have no debt, no savings, and just spend whatever isn't put towards bills every month - which could be sometimes almost 100% of their income, you know? So, to them, 30% probably seems really frugal.

I, personally, have debt to repay, and savings to build, so to me 30% seems almost too much to spend on "choices". I'd rather spend the 20% on choices and contribute the 30% to financial priorities.

In the end, you want to make sure you're allocating enough to your choices to ensure that you aren't living a totally depressing life. I mean, if we all just saved every cent not going to pay debt or bills, we would miss out on the fun things in life that aren't necessarily free. I swung that way for awhile and was miserable.

I also thought it was too much but then I realized that my 30% was too high and I would not achieve my goals of paying back my debts quickly as I needed to feel. so I changed it to 20% and it is a struggle to stay there but a much more realistic goal for me.