Many owner-managers seldom get around to updating their business plan unless they need to borrow money. Some people produce a business plan when they start up, only to leave the document locked away in a drawer or cupboard somewhere, long forgotten and never used.
If you want to maximise your chances of success, you should be working with and updating your business plan regularly.
You should view your business plan as a living document, a tool you use to run your business more effectively. Without having a regularly updated business plan, which accurately describes your business, its market, goals, development strategy and cashflow predictions, you risk drifting from one week to the next, never knowing where you're heading.