You dont have a dog yet?
Yes, he changed very suddenly. I guess it was an adolesent thing and he started testing the boundaries for everything and the lead pulling is the only thing we have never got back on track...fully, despite many many attempts and lots of work on it. At the end of the day, we personally have decided we'd rather use a tool to stop him pulling so we can enjoy the walk rather than spend every single walk trying to re-train loose lead walking.
Dont get me wrong, we do still work on it and sometimes he is really good. But sometimes he isnt and he's a big dog and I am only a reasonably small lady so tools work well here when I don't want to work on it.
So it's not always about NOT training your dog, but being able to sometimes enjoy doing something with them in between training. I dont want to spend EVERY walk practising coz it really ruins the walk for me, and him LOL
ETA, he is the only dog weve never been able to perfect this with. Well and Pippi, but (and this is terrible) I never bothered teaching her a loose lead walk. She weighs 6 kilos so I can barely even tell when she is pulling LOL. Plus, she tends to stop every few steps anyway to make sure I am still with her