hmmm...within 10' you don't have to play as much break unless it's downhill and the green is sloping heavily toward your right or left (speed of the balls).
At 10' I'm looking to sink it or get within 6".
At 20' I'm looking to sink it or get within 1'
At 30' I'm looking to sink it or get within 2'
More than 30' sink it or get within 3'.
In every instance I'm looking to sink it and I don't care how far away I am. In every instance this has to do with speed and break. The closer you are, the less influential unless severe. The farther you are the more influential including double breaks which could mean a straight in aim. As regards distance, a 30' putter - 15' is halfway. 60' - 30' is halfway, 40' is 2/3rds of the way on the swing meter. These are absolutes on a dead flat green and based on you hitting the center line perfectly. The ball will go where you hit it.
Since none of us are perfect, you might pull or push the putt. On a dead flat green, you'll miss but on a green with break, err on the side of the break against. In other words, if you aimed right and the break is to the left, push it because if you pull it, you'll probably miss more unless you aimed too far right. I know. It's tough. On long putts your goal should be within 3' or less. On short putts it should be either in the hole or within 6".
If you follow that, you should always 2 putt.....minimum. It ain't easy but it works.
Pete