This is so weird to me, but sure, customs differ.
Around here kids today have penetrative sex from 12-13 years of age, would you rather they do in school bathrooms, back alleys, bushes, or somewhere clean and safe where they can also get help from a trusted adult if something goes wrong?
Cismale here. It varies wildly with mood and available energy.
Happy, horny and ready for release: I can be done and cleaned in 20 minutes.
Cognitive block and need it for the dopamine: prolly 40-60 minutes.
Tired but happy after a weekend hiking or similar: 90-240 minutes.
Depressed: 2-6 hrs.
Indulging myself for full satisfaction: 2-4 hours. Maybe with another one, 20-90 minutes, depending on mood.