Business Planning - A waste of time?

I'm in week 2 of setting up my new business. At this stage, I have had to deal with the ups and downs of IT systems working and then magically not working. Some of the things that I thought would take no time to do are still outstanding. Other items that I thought would take months to do are done. I had a plan for the setup of my business but so much of what has happened lately has been unplanned. So is planning a waste of time?
I have been advising to businesses for the last 17 years and throughout that time I have extolled the virtues of planning to my clients. Now that I am setting up my own business, I can easily understand how business owners would think that plans are a waste of time. But I also appreciate that my plan has really helped me deal with the unexpected.
I would still encourage anyone to have a business plan and renew it often - probably yearly is sufficient for most businesses. It has helped me stay on track with my goals when things looked like they were going to fall apart. It has helped me keep perspective on the medium to long term rather than the daily issues that I have faced.
So in my view planning helps keep the momentum going in the right direction. It can help you keep driving towards your goals even if you stray off track once in a while. And of course, I would recommend that you commit your plan to writing. Like seeing your final built house months after the plans are finished - it is a satisifying feeling to see the final outcome of your plans come to reality. That's why people go into business for themselves in the first place!