One of the most insidious things to happen to golf in recent times is this idea of pick it up. There was even a smartass commercial about some guys so eager to finish their round (in a golf cart, of course) so that they could drink the brand of beer being advertised that they were saying "pick it up" from a couple of hundred yards out. That's an extreme example, but I can't tell you how many times I've played a round of golf with folks who had one idea or another about why you should not just go ahead and putt it out. For non-golfers, that means that you should actually do what the rules of golf recommend and make sure you have putted the ball in the hole before you consider the hole completed.
The most common assault on the rules of golf is the "in the grip" bullshit. This is an agreed-upon cheating mechanism whereby a group of golfers will decide on the first tee (or, even worse, they've been doing it so long that it's assumed) that any putt which is no further from the hole than the length of the shaft of the putter can be picked up with the assumption that it would have been holed. There is so much wrong with this idea that it is hard to figure out where to begin.
First of all, it's cheating. Let's get that established before we continue. If you do this, you're a cheater.
Second, who is to say that all of these "in the grip" putts would have been holed if the player had actually had to putt it out? I can guarantee you that on some of the courses I've played, from the unpredictable poa annua greens out in California to the grainy Bermuda greens in Florida to the slick bent grass greens in Chicago, your average golfer will miss at least a third of these putts "in the grip." That's like shaving 6 strokes off a round of 18 holes. So, when you tell your friends that you shot a career-best 88 today, the first question they should ask you is, "Did you putt them out?" This is one of the ways hackers will artificially lower their handicap. An honest golfer will not take liberties such as this with the rules, and you can't imagine how crazy it makes them when some hacker, when asked about his handicap, says, "I'm an eight," when you realize that he couldn't break 90 (let alone 80, which is what he is claiming by this statement) on his best day if he played by the rules of golf.
Third, there is no one definitive length of this gimmie distance. Every putter is different. The norm is to measure by way of anchoring the putter head in the hole and seeing if the ball lies within the shaft of the club before you get to the grip. So, if your putter shaft has a couple of more inches than your buddy, you are cheating him out of a potential total of one 36 inch putt each round. Put a golf ball down on a fast green with a hard break one way or the other from 36 inches and see how many times you make that shot.
There is only one way to play golf correctly. A large part of that one way is to putt it out. It really doesn't take that much longer, and you'll feel a whole lot better about yourself.