1. You can certainly experiment with 100% positive offset. It is easy to set up, and it can make pretty patterns on your skin. Please read: https://www.spooky2.com/forums/viewtopic.php?p=43156#p43156 for a post I made on the matter.
Hulda Clark's recommendation needs further clarification. What is a positive offset? Is 100% negative offset ok too? And what is the difference? Perhaps you could enlighten me.
2. I use the Hulda-Clark-Preset with 100% Offset a lot and never got burned.
I use the hand cylinders and not the tens pads.
In my opinion Linda Ray has written here in the forum anything you need to know about turning a spooky-generator into a hc-zapper safely.
I think a warning about the possibility of burns when using 100%offset together with tens-pads is useful.
To say do not use it in contact-mode is somehow misleading.
But I also think for a quick guide it is maybe better to go for "the safe way".
3. Also, in order to avoid burn that usually you get from using positive offset with TENs pads, you might want to do that with a foot bath. In that way, you won't ever get burned and you can do it for longer times. Positive offset over night is not recommended as that's for certain that will end up in a nasty burn. I know, I learned my lesson the hard way.
For more details, please check the link: