[YodasLuke]

Our practice green has a really small hole cut in it. It's barely bigger than a ball. The drill is to sink two putts in a row from 1 ft, 2ft, 3ft, 4ft, and 5ft. As long as you make one out of two putts from a given distance, you can stay there until you make two in a row. If you fail to make at least one out of two, you go back to the beginning.

After getting two in a row from 5 feet in the small hole, I went to a standard sized hole and did the same drill, this time extending well beyond 5 feet (in one foot increments).

If you don't have a small hole on your green no problem, just use a regular hole.

How far can you go before going 0 for 2?

I haven't tried that one, but I will.
I putted on a chalk line once (a super's worst nightmare). They don't like you standing in the same place on the green the whole time. But, from 15 feet, I made 39 putts in a row. It was a straight, uphill putt. And the chalk line made it easy. But, the stroke still has to repeat. I honestly missed the 40th putt because I lost my focus. After doing the drill, I could see an imaginary blue line on all my putts.