It depends on multiple factors:How big is the airport ?
There are more flights and passengers at bigger airports.How busy is the airport when you travel ?
Do you travel during a peak ?What baggage do you have ?
Do you have only a cabin baggage or do you also have a Check-in bag, so you need to go to the check-in desk ?
Sometimes there are long queues and delays at airports, because of security check or baggage check at the check-in desk. It is usually recommended to arrive at the airport 2 - 3 hours before the departure of your flight. If there are some delays at the airport and you need to go to the check-in desk, because you have a check-in bag, then it is better to be there even earlier.
When there are some delays, you will probably get a notification email: