Most start-ups can get away without a written business plan because the founders have everything that would be in a plan in their head. In larger organizations

Most start-ups can get away without a written business plan because the founders have everything that would be in a plan in their head. In larger organizations you absolutely need to use them as the people deciding what businesses to be in aren't the people executing the ideas. So "Don't write a business plan [if you're a start-up]" is what the title really should be. One thing to consider, write big goals / milestones down and ask yourself each day, "Is this activity getting me towards our next goal?" -- if not stop doing it. Without planning you can quickly get distracted by shiny objects and short term revenue. If you're going to spend significant time on something that isn't a current goal have a quick chat with your team and get agreement to change the goals -- this isn't "writing a business plan" but this is "business planning" -- just because you don't do the former isn't an excuse to not do the latter.