I've seen too many examples of code at work where you can tell a developer has just come back from a training course on design patterns.
It's usually an overly complicated solution / 'pattern' that has been applied to solve a simple problem, because you've learnt these things right, so you should use them where you can. Rather than sticking to the simplest solution. Less code == easier to understand (for yourself _and_ others that will have to maintain your code) == less chance of bugs slipping in.