Are you a meticulous planner, or do you jump straight in?

This is something I find quite interesting. I've noticed that when it comes to any form of entrepreneurship, there are two types of people (excluding those who never gather the courage to go for it, etc.):

1) Those who plan meticulously - these are the type of people who truly engage with market research, writing business plans, planning their marketing moves, writing tonnes of content to be released gradually, and so forth, before they actually start a project

2) Those who jump in, and plan as they go - these are people who get an idea, and start the business/website straight away. Rather than planning for eventualities and preparing for the first few months prior to starting up, they'll do it all as they run along - sometimes with dire consequences!

Both of these have their obvious advantages and disadvantages, but which category would you put yourself in? Or would you define yourself altogether differently? Do you wish you belonged to the other category, and are you trying to change? If so, why, or why not?

Thanks! I look forward to seeing how the average DPer goes about things.