There's no single answer to this question...
If I shoot a qualification course at work and need to clean my Glock before getting back to work, I can have it done in 5-7 minutes. If that same gun got soaked because I was fighting someone in a creek (it has happened) or because I was standing in the rain for two hours (that's happened more often), then I usually spend more time detailing the gun.
My precision rifles (bolt guns) only get cleaned occasionally. There's no need to clean these rifles every time they're shot, and doing so only makes things harder in the field. The action gets cleaned more than the barrel, and barrel gets cleaned every 150-200 rounds or so. When I do a full cleaning, it probably takes me 30-40 minutes.
AR-15's are a pain in the butt. If I want to detail clean an AR-15 I usually figure it's good for an hour of my time. A quick clean and lube might be a ten minute deal, but that doesn't involve getting carbon off of the bolt, or getting the weapon cleaned to an "inspection" level.
Oh, and when I shoot corrosive ammo through my old 8mm Mauser, I'm probably looking at at least an hour for cleaning it. When I shoot modern ammo through that rifle I'm looking at about a 10 minute cleaning job.