So, to make sure I have this right, these particular mods are to improve performance of the device by ensuring that the wick doesn't dry out, and to allow more liquid into the cart, right?
Yup..
The basic functionality of the ecig is...
Battery provides electricity...duh
Atomizer uses electricy to vaporize the liquid
Cartridge holds the liquid.
The main "problem" faced by ALL ecigs, is getting the liquid to travel from the cartridge to the atomizer.
Efficiently.
let too much liquid get to the Atty, it floods and can't get hot. And juice leaks everywhere.
let too little liquid get to the Atty, then you get that burned metal taste, and can damage the atty.
It is a very delicate balance to get the right amount of liquid to the atty.
Most mods are meant to maximize the efficiency of the liquid travelling from the cartridge to the Atty.
And there are many mods. For me, I find the PTB to be the best filler material that allows the most efficient wicking.
Also, many people bypass that problem completely by Dripping.
Just removing the Filler material from the cartridge completely, and carry around a small bottle of juice with them. Drip a few drops directly onto the atomizer, replace the cartrige (without filler), Vape for a while till you notice the flavor/vapor decrease, then drip some more.
Hope that helps.