I put the cool touch wand on my Leva because I thought it would help (hole configuration) with my texturing.
Theres no substitute for practise. When I was 10 hours straight on the Minore at last years Aroma Fest I was pretty bloody good by the end of the day.
If you get hot thin milk there arent enough bubbles.
I use the 300ml jug 99% of the time.
Fill to a few mm under the spout mark.
Sink the wand to one side to get a whirlpool happening then break the surface to get the "ch ch" happening.
Youll see when the milk has increased in volume and then wand back in to finish heating.
Im no expert either yet but I think the amount of increased volume makes a difference. Having enough time left to mix this with the rest of the milk by whirlpooling or folding before its hot enough is my gut feel on what makes the difference between thin/perfect/thick milk.