How long an overdue flight will affect your flight depends on airline regulations and government regulations. Generally speaking, if a passenger arrives at the airport late before departure, he may be unable to board the plane or be asked to change his flight. The specific circumstances may vary. The following are descriptions of some common situations:

1. Domestic flights:

- Regular flights: For domestic regular flights, airlines often require at least Arrive at the airport for check-in in one hour. If you exceed this time, you may be considered a late passenger and may not be able to board the flight.

- Delayed or changed flight: If you are late because your flight is delayed or changed, passengers can generally contact the airline for help and solutions. The specific handling method will be determined according to the airline's policy.

2. International flights:

- Regular flights: International flights usually require passengers to arrive at the airport to check in at least two hours before departure. If you arrive late, you may not be able to board the flight.

- Cross-border flights: If it is a cross-border flight, passengers also need to pay attention to the entry regulations of the airline and the destination country/region. Some countries may have stricter requirements for late arrivals.

To sum up, how long the overdue period will affect flying depends on the regulations of the airline and government regulations. Generally speaking, if a passenger exceeds the arrival time required by the airline, he may be unable to board the plane or be required to make corresponding adjustments. It is recommended that passengers understand the airline's policies and requirements in advance when planning their itinerary, and reasonably arrange their arrival time at the airport.

Note: The above answers are based on general conditions and common regulations. Specific conditions will vary by airline and destination. Since no specific conditions are provided in the question, the above answers are for reference only. For accurate information, please consult the relevant airline or official airport channels.