Tricky issue here is: it will not end with a time cost headache only. Because projects may fall into scope change if it gets longer than planned. In other words, go to market needs force scope change in longer times, because market is not static. So, what can be done, in order not to fall this circular loop of this quality problem. To avoid this mentioned risk; projects may be planned in phases or in small projects which have business deliverable in each small units.
The agile development techniques are awesome and successful, because they are smaller in size.
There is no way for huge size projects in business. So, divide and conquer! Close the project as soon as possible if you can, divide into phases if you can.
