In my first work, there was one team for testing and support. Each of us was both testers and first line support for our team’s projects.

It was the exciting experience that shaped my whole view on testing and our value.And it is my strong belief that all testers should experience it at least once in their career.

„A common mistake that people make when trying to design something completely foolproof is to underestimate the ingenuity of complete fools.” – Douglas Adams

It was a humbling experience.: I’ve spent around half a year testing our new product. Then after seeing it going live, I was supporting it as the first line.
The cascade of bugs found by users completely shattered my view of the quality of my job.
Some of those issues went completely unnoticed by me. Other I knew, but I wasn’t able to make the convincing case to dev and business for fixing.

It is the easiest way to make newbie understand the biggest truth about testing: 'No matter how much I would test, bugs will be there.’

Power of the crowd

Few testers won’t be able to think of all ideas that can rise in mind of any user. And add to it ingenuity of users, and you have powerful tool bug finding tool. This is the reason why companies want to put product as fast in hands us many customers possible.
Testcase vs. Reality

Test cases have little value. Most test cases I have seen haven’t much in common with reality. They were either poorly updated or reflected the state of up before some changes or were too „sterile” for real environment. I have started to feel very fast that writing them was a waste of time. Their only value was that I could show them to my superiors. 'Look I am doing work, here is proof.’ But their actual value for product quality was minimal. (There is an argument here that that was my fault. I was self-thought, and I didn’t know how to write proper test cases. But now six years later I still stand by this point)

The Front is Hell

I was fortunate there was limited number of people that could call me, but I have seen part of that hell that is Support.
It helped me rank bugs. Accessibility bugs and user experience became much more important to me? Why? Cause if a user has difficulty with the application, he will either gave up or call support. Remember each support call is a cost for the company.

So what can you do?

Ask your boss to put you in support for few weeks. You will see what going on there (best moment is after release some important feature by your team)
But what if that is not an option? You can always make some friend in support team see how stuff is for them. In one of my previous companies, I was regular chatting with about how stuff works in production. IT was good

Okay, that won’t work if this is a third-party company. But you still can ask contact people for some data.

Edit I have made a presentation on this subject you can read about it in my relation from Testwarez