Almost every failed software project we have been asked to rescue failed for the same reason. Nobody sat with the people who would use it.
The specification described the process as management believed it worked. The build matched the specification. And the exceptions — the ones the team had been handling by memory for a decade — had nowhere to go. So the spreadsheet came back, quietly, alongside the new system.
We start in the other order. We sit with the scheduler, the accounts clerk, the person who answers the phone. We ask what breaks their day. Then we write it down, agree it in plain English, and build against that. It is slower to start and much faster to finish.
The rest is craft: readable code, honest estimates, a demo every fortnight, and documentation good enough that you could replace us tomorrow. We would rather keep clients because they want to stay than because leaving would be painful.