Another way to get a starting point for what voltage to vape is this.
Ohms +2 -.2
Ex:
3 ohm atty add 2 = 5 then deduct .2 from 5 = 4.8 volts now go up or down a bit from there depending on the juice and how you like your vape. But this keeps you from having to look at the chart so much. If it tastes a little burnt, go down a couple notches in .1 increments If you aren't getting much flavor/vapor, go up a couple notches at a time.
As you can see from my siggy line, I do think vv makes a world of difference! Plus you don't have to worry so much about which Ohms you're getting when you buy a juice holder. First time I bought some ce3's they accidentally sent me a higher ohm than I ordered, or I may have clicked on the wrong one. Without a vv, that would have been bad, but with it, I could put enough voltage to them to make them taste good.