If you're always settling for "good enough," you're not going to challenge yourself to do great things or become a real expert at anything. 

As writer Scott H Young points out, "stopping at 'good enough' is an easy way to ensure you'll never accomplish anything remarkable." It's hard to be fulfilled when you approach everything as "good enough".

Young breaks down perfectionism to different types: good and bad, or short-term and long-term. Short-term perfection is when you're obsessed with a small project that doesn't necessitate it. Maybe you're devoting too much time to a first essay response in an exam, or polishing your resume instead of sending it off. This is bad perfectionism, and a perfect example of when "good enough" is indeed good enough (because it helps you move forward).

However, in long-term projects, perfectionism is crucial. If you want to master something, you have to keep pushing yourself to explore new ways of doing things. You'll always settle for something that's acceptable, but not great, and you won't improve.