@antonio13 My problem with this solution is that we want our dog to sniff around. We don't want him walking heel. (I mean, no harm in heel, I'll reward the heck out of him if he does it naturally, but sniffy walks is what we aim for.)
I've been trying the slow down and stop way, doesn't seem effective. I also have tried the turn go the other way if pulling, and if I do that a few times in a row, he seems to grasp the concept. (I praise him when he turns with me, and try to make it a fun thing.)
SO has had vacation and has been walking him more. I usually do the 2 m leash, he usually does the flexi leash (he hates the short one). He walks slower than I do, and I only barely match my pup's comfort speed. It seems the more he's on flexi leash, the worse the pulling gets. I get him back into line after a few walks, but it's a bit meh we can't seem to figure the walks out properly. I suppose I should try teach him how to handle walking slower, but think that'll be quite annoying. Perhaps I'd be happier with a 3 meter leash.
We did a pack walk the other evening, that is, me my SO and our dog. I held the 2 m leash, we walked my SO's pace. SO MUCH PULLING looooordy lord...