All my guns get clean with in 48 hrs of using them . Not cus 48 hrs means anything other then to me . 2 reasons for this . 1) I love cleaning and or just working on my guns . 2) If I don't clean them with in that time I'll forget and never clean them .
As for my ARs I'm not sure how long it takes me per rifle . If I were to put a # on it i'd say 30 min per rifle . I like to take my time that way I make sure I get in to every nook and crany . When I'm done they are pristine ,lubed up with grease or slip 2000 EWL 30 . I like to use the thick stuff so there is less evaporation and run off While sitting in the safe for long periods of time .
By doing that I know I can at any moment grab one and know it's ready to go that 600 rounds others have talked about . You never know when you may have to go that distance and to already have 5 or 6 hundred rounds worth of dirty in it does not sit well with me .
That pretty much goes for all my guns . All though I have skipped cleaning when I was going to be shooting my 22lr in the next day or so . I'm not as picky about my 22lr but when they get cleaned thay get the same treatment as all my guns .