You need to arrive at airports well before your flight as there are a number of procedures you need to complete before boarding: check in, security check, and perhaps immigration control. You are ultimately responsible for arranging a timely arrival at the airport. '''DON'T wait until just minutes before the flight's scheduled departure to act'''. Check-in or baggage drop closes approximately 40-60 minutes before departure and if you have not checked-in by that deadline for whatever reason, you may no longer be accepted for travel. Conditions affecting ground transport (e.g. heavy traffic, transport strikes, fog) are not valid reasons for missing a flight and expect limited relief from airline staff if these happen. You should consider these scenarios beforehand. Moreover, please '''do not argue with staff''' on trivial issues that you were supposed to be responsible for in the first place, particularly punctuality and required documents.
It is also important to understand that requesting for check-in, boarding or even departure to be extended by just a few minutes is not a simple matter. It has wide-reaching implications. Airport staff need ample time to sort out all issues and paperwork for a particular flight to ensure everything is in order. Last minute check-ins can even mess-up the flight plan (including amount of fuel required). That is not all: a few minutes of delay may cause a flight to miss its take-off slot, and it may take some time - ''possibly several hours'' - to secure a new take-off slot. All the other passengers will unlikely be happy when any of these will happen.