The Time it takes to play a round of golf depends on the length of the course. If there are a few par 5's and you play a foursome give yourself 41/2 to 5 hours due to a 9'th hole break for restrooms and snack. (assuming carts are being used) walking can take longer.) Courses that you can buy beer on the course from the cart kids can take even longer.
If you play an "average" course 18 holes should take about 4 hours up to 4 1/2 hours. Playing in under 4 hours is possible if there is no one in front of you and you play fast. I can play 18 holes in under 3 hours walking if I'm alone and one one else is blocking the way. If you are playing over 5 hours it's a slow round. If you are playing over 6 hours (I have in some tournaments) it's a nightmare.
