Well, yes you would have to rewick I suppose when you are first trying them to see what they taste like, and whether you like them or not. But once you get the hang of it and know your flavors good enough, its not too hard to choose complimenting flavors and get them to change on a dime. I do this all the time, start out with a lighter flavor and work up to the strongest and such.
Of course if you insist on going to opposite ends of the spectrum, some flavors can really screw with others, and once you go all VG, nothing with PG will be the way its supposed to be. I find the VG flavors tend to really stick in the wicks, so those I drip last just prior to wick change..
Good luck. Dripping is the epitome of vaping. It does`nt get any purer.