Its no biggie if its not that tight and moves a bit. It'll still wick and vape well. With a rta (especially with a longish chimney) it don't matter that much for me. When it comes a rda though (especially when the coil is close to my mouth) I will definitely wick it on the tight side.So it doesn't always matter if the cotton doesn't move relatively freely back and forth? I felt some resistance when I was settling the wick, but it did move fairly easily.
I reached a point a while ago where I had enough of spitback so I started looking around for options. I came apon a video of Morton Oen on Utube about it. He did some tests and comparisons and concluded that the harder the better.
That's when I tried it myself and it works beautifully. A hard and well stuffed wick eliminates air pockets that causes juice explosions. It also wicks better when harder.
Lately I don't wick THAT hard anymore as its time consuming and a bit of an over kill. Was good to prove it to myself though. Now I just wick it as tight as I can in the shortest time.
After a while it becomes second nature...kinda.