Hello Reijer59

I made the experience that when I blow the tissue my airstream direction was with milk spout more straight then without.
I think the bottom lip is more relaxed while playing with milk spout
and for me it is easier to control the corners.
One other effect is that milk spout avoid to pull the bottom lip inside under the upper lip.

Hope that will give you an idea Rey we practice milk spout.

Regards
Hajo 🎺