In theory, doing the same thing and expecting different results is silly.
There’s a quote (often wrongly attributed to Benjamin Franklin) that says doing that is the definition of insanity.
But the rate things change on the internet it’s often the case that something you did last week or last year gets totally different results even if you’re doing the same thing as you’ve always done.
For instance, if you’re still using MySpace rather than Facebook your audience will have dropped along with the relative usage of the sites.
And if you’re unfortunate enough to be a website designer then you’ll know that you haven’t changed your code but the browser you’re using has done so and your nicely designed page is now broken. You’ve done the same things you’ve always done but you’ve got different results and maybe even a few sleepless nights whilst you fix stuff that shouldn’t need fixing.