Iterative work is THE way to work in large legacy codebases. The minute you wade into the code, all of your planning is moot. You don't know what's lurking below the surface. No one knows what's lurking under the surface. Except maybe Dave, because he vaguely remembers about 15 years back talking to some guy who wrote some code 30 years back about it.
Greenfield, absolutely design up front you lucky devils, but iterative is the way otherwise.
Greenfield, absolutely design up front you lucky devils, but iterative is the way otherwise.