A lot of data entry is hard to unwind and correct in those kinds of situations; where a multi-step process is fully filled out and submitted based on key initial data that's later found to be wrong/invalid.
But I find that you often wind up having to write code to deal with that anyway, to handle cases of inadvertent user errors.
(e.g. I reserved a flight, room and rental car in Kansas City, KS -- but I was supposed to be reserving a flight, room and rental car in Kansas City, MO.)
So while I'm intimately familiar with and sympathetic to the challenge and complexity involved; I don't know that it's additional challenge or complexity.
But I find that you often wind up having to write code to deal with that anyway, to handle cases of inadvertent user errors.
(e.g. I reserved a flight, room and rental car in Kansas City, KS -- but I was supposed to be reserving a flight, room and rental car in Kansas City, MO.)
So while I'm intimately familiar with and sympathetic to the challenge and complexity involved; I don't know that it's additional challenge or complexity.