I remember interviewing a BA (business analyst) who had just come off of the INCIS project. She said their entity model was enormous, with tens of thousands of entities.
I couldn't understand how any project could have so many entities, let alone how anyone would ever hope to code up such a thing.
She said the commandment to the analysts was to model everything so they did, just like they learnt in data modelling 101.
So (INCIS was a project for the NZ Police), e.g.:
- A police station has zero or more cells
- A cell has one or more doors
- A door has one and only one key
- A door has many bars
Another data point in INCIS - my sister at the time worked in the police. Her workplace ran out of pencils (they did a lot of note taking with pencils and paper). INCIS had so thoroughly depleted the police's budget that there was nothing left for...say.. computers with email and the like.
The software itself, before fixing it, cost $182mm and covered payroll for 90,000 teachers. That's over $2000 per teacher. It cost another $45mm to fix it after this.
I was working with one of the companies that came along to replace one part of the system with a much smaller component that just handled that individual piece and vividly remember the meeting with the IBM team. They had no code to show me, but they handed my a massive folder - probably verging on 10cm thick of use case diagrams. So many little stick figures staring up at me I was awestruck - but not in a positive way!
[0] https://en.wikipedia.org/wiki/INCIS