It is difficult to explain to a division director that they do not have sufficeint capacity (enough qualified programmers) to compete features within a set time budget. The old joke goes, "It takes one woman nine months to produce a baby. But: what if we just put nine women in a room for one month!?"

What has happened to me in those cases is that Architects lumped on a lot of extra nice to have things which would certainly have made us fail the time constraints. It was completely un-agile and I only got things done on time by demonstrating very clearly that time sensitive work is not the place for grand refactoring and at last winning over the main architect.

When there's a time constraint one has to be able to winnow out the real must-haves from everything else.

Some tasks may simply not be possible or not in the time available. Agile just sort of tells you that - you can see how things are going and if they're going right or not.

Then you have a choice - find something to cut out or accept a later date. This is a mode of thinking that I find non developers have difficulty accepting. They want it all and they want it now and their modus operandi is to keep pretending that it's possible and suggesting that if they shout and stamp a bit that it will somehow rescue the situation.