How to determine if something is an artificial deadline? Because if it were a real deadline with significance to the business, they'd pull more hands on deck, remove roadblocks relentlessly day after day, and even offer to take portions of your work on themselves so that the deadlines can be met.
If they are not making such moves, rest assured that the deadline is not critical - but only required for some BS stack ranking, or for the management's own promotion. They WILL fire you after putting all the work if it fits their BS processes.