The biases are probably the biggest road block. You make an assumption of what is wrong and start looking in the relevant code. There thousands of if statemen

The biases are probably the biggest road block. You make an assumption of what is wrong and start looking in the relevant code. There thousands of if statements that all start somewhere at the top ,creating a big fork. It's easy to get stuck when you are looking on the right side when the issue is on the left. Always understand that your assumptions can be wrong.