It sounds odd, but sometimes to see details, you need some distance.
Yesterday I was at the pharmacy (for those of you in the U.K., the chemist...) to pick up a prescription. I also needed to get a small jar of Mentholatum.
There were rows and rows of items just for colds and flu!
I wasn't seeing Mentholatum anywhere. As a tester, I realized I was in a "needle in the haystack" problem. I was about to give up, then I noticed the line at the counter had only one person in line, so I got in line.
While I was waiting, I looked back at one of the rows of shelves and from about 20 feet away started to scan each shelf. Then, I spotted the small jars on the bottom shelf, almost hidden from view.
Standing one foot away, I couldn't see the lower shelf at all.
It reminded me of a time when in college, I had an engineering professor who would always tell us, "You are too close to the problem. Step back. Think about it from a distance." Most of the time that was exactly way we couldn't solve the problem!
It's the same with testing. Many times, we don't see defects because we are too deep in the details. We need the bigger picture sometimes.
Just something to think about...
Have a great weekend!