Wow! Thank you all for the warm welcome and your experienced advice! 
I think what I'll try short term is to get the prefill and on days when I "hit a target" try some dripping/topping off. Once I learn to detect the flavor change so I don't burn the carts, maybe I can move to some cleaning and true refills or filling blanks on the good days.
One last question on the topic if I may: Has anyone noticed any difference in the useful life (juice-wise) of a Wow vs. Premium vs. Cool cart?
Oh and I shoulda been more clear.
I started with the PT but use the manual XL's 95% of the time since I got the kit. If you get too heavy on the 5v PT with a Wow cart, your lips will feel like you're huffing a hot engine tail-pipe <sizzle>. 
I think what I'll try short term is to get the prefill and on days when I "hit a target" try some dripping/topping off. Once I learn to detect the flavor change so I don't burn the carts, maybe I can move to some cleaning and true refills or filling blanks on the good days.
One last question on the topic if I may: Has anyone noticed any difference in the useful life (juice-wise) of a Wow vs. Premium vs. Cool cart?
Oh and I shoulda been more clear.
