Do test cases really drive you to defects?

Testing an application have many required tasks, like writing test plan, design test scenarios, writing test cases and many many more. And when you are testing based on those checklists what are you getting? Defects? Really, how many? May be they are covering application's requirement but do they cover application's functionality? To be honest this path never helped me much, I never find a worthy defect after all of these works. But surprisingly when ever I am testing any application my insight lead me to defects. And to be a lot more honest whenever I am testing, I put myself in an user seat or customer's seat very rare.

According to me Exploratory testing is the best practice for software testing, you always come up with good defects and you need to educate yourself to know that it is a defect. So, my advice would be to listen to your instincts and recognize defects at first look. That would help a lot more than any test suits.