I really don't seem to use any more cotton to make a scottish roll type wick than I do with a "standard" wick. Just looks a little bigger from the stretching and rolling. Super fluffy. But I make mine so they thread through the coils easily. then after trimming and fluffing the ends, it looks huge.
I used the scottish roll for all my rda builds for a while, then thought maybe it is just a gimmic and I should just do a regular wick. Switched back for about a week. Then went back to the roll.
I get twice the hits per re-drip with the scottish roll. From 10ish with standard to 20+ with the roll (same amount of cotton mind you). I find it gives a cleaner flavor too, but might just be me. Scottish rolls absolutely hold way more juice though.
Have also found as someone mentioned can vape them to cotton white. Could never really do that with regular wicks. Seemed to kinda "trap" some juice in parts of the wick. Can't be an indicator of good wicking flow.