As a matter of fact, did you know that the Small Business Administration says that 50% of small business owners will fail sometime during their first 5 years? There are lots of reasons but one big one is that owners don't have a plan. Another is they have picked a product or service that doesn't have a big enough market to sustain their business and sometime during their future they will run out of customers.
Then there are the moments when something seems to be going wrong, when one or more areas of the business just don't seem to be working. Cash flow is anemic or the marketing message is flat. Perhaps customers have shown a marked interest in only one particular product or service, ignoring all your other offerings. This means it's time to revisit your business plan, more precisely it's time to revisit the questioning process that helped you craft your plan.