"you save a lot of time by not planning things you don't need that way" Yes, but on the other hand you will lose time if you do not plan those things ahead of t

"you save a lot of time by not planning things you don't need that way" Yes, but on the other hand you will lose time if you do not plan those things ahead of time that you can plan ahead of time. It's much cheaper to catch ill defined requirements while planning on paper than once the constraints reach production and people start implementing features and tests based on them. Although you cannot plan _everything_ there is always _something_ you can plan - and should plan. Unless you have a spec or a plan at day 0, you do not have a documentation platform available when the shit invariably does hit the fan and you need to do the learning-organization-disco and facilitate a change to your product because some real world constraints were not known or acknowledged before hand.