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.