I was part of a team that the developed a workflow management system for managing telecom's infrastructure. We were really quite proud of it, it pushed our boundaries during development and we learned a lot of new skills. It was implemented exactly as per the clients spec.

It was also quite expensive, my employer billed them €300,000 for the work.

They accepted it.... and then didn't use it.

There was some use in the first few weeks, but then it petered off - despite this they kept paying us to manage the hosting and suuport of the system.

After a few months our manager approached them to ask if everything was Okay. Their response was to say the thought it was an amazing system, but now they realised it was way over-specced and using it was more of a burden than they expected it to be.

I suppose it was the software development equivalent of ordering the biggest thing on the menu and then regretting it.