The accepted standard time is four hours. That's a foursome of players with 10 to 20 handicaps on a standard 18-hole course with groups on every hole but not too many to cause a backup. Players who shoot par or close can finish a round in under three hours, even with a twosome. Players with a handicap of above 20 can take more than five hours to play, especially if the course is busy.
Players who shoot closer to par can finish in under three hours depending on the course traffic; their shots will probably be more accurate and carry a little farther, decreasing the amount of time spent traveling and looking for balls.
Courses differ. A round of 18 holes obviously takes longer than nine holes. Par-3 courses (total par 54) generally take less time to complete than a regulation course (par 70 to 72). Course yardage matters as well: Courses with long par-5s (550-600 yards) and 4s (400-465 yards) generally take a little longer than courses with shorter holes.
Driving or Walking
Players who ride in cart should take a little less time to play than those who are walking, though par and better players can finish in 2 1/2 hours walking without a backup on the course. When riding, sometimes it is best to drop a player off with few clubs at his ball, then drive to another ball to hit. This could save more than a half-hour each round.
Size of Group
Group size makes a difference as well. Foursomes take longer than twosomes or a single, although sometimes smaller groups will pair up on the course, extending he length of the round.
Golfers should always follow proper etiquette to not hold up others. Unless the course is empty, do not play more than one ball. Do not record your score while on the green; go to your cart or the next tee box. Play ready golf: Line up your shot while waiting for others to hit; decide on club selection, weather and wind conditions and your shot line before addressing the ball. After addres, you should hit within 30 seconds. Always be mindful of players behind you; chances are they don't want to be on the course all day either.