Canada

Having curled myself, I can assure you it does not...and if it did make a difference, it would almost certainly be negative, since you're giving up any semblance of control that you had on the actual throw. There's not going to be some "precision poke" that magically steers it where it needs to go. But don't take my word for it.

Does it make any difference?

"No. The double-touching that I've seen has been incidental contact, and that's fingers brushing or hand brushing on a 40-pound piece of granite," said Eugene Hritzuk, a Canadian curler based in Saskatoon who has been involved in competitive curling and coaching for more than 60 years.

"What can fingers brushing against a 40-pound piece of granite do in any event? You need the palm on your hand against that stone to do anything."

Delivering a stone entails acute skills to slide on line and on pace, he said.

Once sliding on target and at the right speed, releasing the stone and then touching it with any force would cause it to veer off its intended line and speed, Hritzuk said. "That would not be advantageous to good execution."

Canadian curling commentator John Cullen, who hosted the CBC podcast Broomgate: A Curling Scandal, said most top curlers will say that double-touching has no effect on the stone.

As well, most top curlers will double-touch at times and don't think it's a foul, he said.

"The idea that a top curler would let a rock go and then want to try to adjust it with their finger —it doesn't seem like there's any way you could get an advantage from that. It feels like it would be worse."

But as I said, the rules are the rules, and I don't think it's wrong to enforce them.