Of course, sometimes companies adopt the wrong strategy. Before the days of iTunes, record companies resisted every attempt to distribute digital music, even going so far as to sue consumers of their products. They were trying to protect the highly lucrative and profitable CD business. Unfortunately, it was so easy to rip and distribute music that none of the protections they put in place worked. Enter Steve Jobs and Apple who created a marketplace for digital music. The record producers had to join in, CD sales went off a cliff, and now Apple gets a huge cut of every song sold through iTunes. Could the record companies have developed their own marketplace so that they wouldn't have to share the revenue with Apple? Maybe, but their strategy was to protect what was in essence an unprotectable business.
The business world is littered with failed strategies. Technology changes, customers demand something different, cheaper and better competitors show up - lots of internal and external events can challenge the business strategy. The best companies review the strategy early and often. How do you know if you have the right strategy? Go back to the vision and figure out what has to happen to make the vision come true. Some of it is guesswork and optimism. But no business ever succeeded without a strategy.
Changing strategies too often can also be a problem. A company starts out wanting to be the high quality, low volume, high price producer of widgets. But nobody is buying. So they try to become the 'celebrity widget' and pay a lot of bucks to some aging movie star to endorse their widgets in an expensive ad campaign. That makes the movie star rich but doesn't move widgets. So they decide to sell mass-market widgets at a mid-level price, but there is already a lot of competition and they can't differentiate their widgets from anyone else's. Then they find that nobody needs a high quality widgets, the cheap ones are just as good. So the company changes strategy to produce low cost widgets, but they find the market is full of cheap Chinese widgets. Lastly, they try to license their 'superior' widget-making technology to the other manufacturers. Doom.
"Strategy-of -the-Week" companies aren't fun. Companies that change strategies over and over don't understand their markets, or can't explain the value of their products, or what problem their products solve for the customer. And changing strategy is expensive. They burn through a lot of money very fast.