If you wet tumble with SS media it scrubs the carbon out of the inside of the case neck. Applying the dry powdered graphite that is nothing more than a fine powdered carbon re-coats the case neck.

And I watched a YouTube video showing the application of Imperial Sizing Wax with their fingers to the outside of the case and then using a Q-Tip to apply it inside the neck.

So it depends on how you clean the inside of your case necks. I'm forming Lake City 7.62 case to .243 and using Hornady Unique like above using a Q-tip to apply Hornady Unique to the inside of the neck. I then clean the inside of the neck with a case brush.

If just neck sizing I use the dry powdered case neck lube (main reason for dry neck lube) and sometimes after wet tumbling to replace the carbon inside the neck. Some competitive shooters say that wet tumbling effects bullet grip because the bullet bonds to the case neck.