I birdied 14,16 & 17 coming down the stretch today at TPC Myrtle Beach to finish with 74 from the tips and that course is literally one of the most difficult and extremely long especially with recent rain.
Think about it this way - if you are in a tournament and have to putt everything out, you probably have 50 putts in a foursome between 1-3 feet. If each person takes 20 seconds to look at his putt, practice stroke, putt, pick up your ball, that's 17 minutes. That doesn't include the time to mark a two footer that you would normally pick up but you're not away and you'd rather wait to putt out. May be more like 30 minutes. Putting out really slows things down.