Maybe for some developer's who got a new job or a new position in a new place, not only developing a new application but he/she must and have a duty to maintain other application that had been running for many times and may be many years.
It's important that the Project Leader must forcing the developer to make a well documented project document.
As this happen to me. I have to shoot directly to the database from a thousand member data from the other database type - in this case .DBF - so, i have to converti it to the csv and then load to the database. But, what is the important? I have to know the database design firstly. What happen if there are no documented. I have to trace and re-engineered a database so i can tracert the logic or relationship of database.
It's something difficult. So, keep your project well documented.