efficiency

So you want to be more efficient. Here's the key:

Only do what's really important.

Sounds too simple?

Let me explain:

Suppose that you have an application where the user can enter an amount. Your tester identifies that this will throw an exception when the value is very large. Now in the business context, a value this large will never be entered*.

So you investigate the issue, then implement a solution and then it has to go through testing.

Seems innocent enough.

Except that all of that time and effort could have been used in solving an issue that really is important. Granted that this is a simple example, but if you are doing a lot of these, then you're not really adding value. And the time should be allocated to higher priority issues.

* This example assumes that you are sure that the business will never need this functionality. You should never arbitrarily assume that something like boundary checking is not necessary. It normally is. And this is just an example, so take it easy on me!