I am currently using King Cole Riot DK in a very bright colour combination called Neon.
The colour combination is fantastic, there are long runs of each colour, changing gradually into the next colour, going from the darkest indigo through to a light green and then gradually back to the darkest. I reckon a full colour change must take about half of the 100g ball.
I know it is not unusual to find a small knot in a ball of yarn where the yarn had broken during the production process and someone has tied it together with a neat knot. Normally I find this a bit annoying but it is easy to work around. With Riot it is much more challenging; the first break tied indigo to bright green, I had to discard 15g of yarn before I could match it. On the plus side when I came to join the 2nd ball of yarn I had only to discard a couple of grams before I had a match.
But now I have found a knot in the second ball, it looks as almost a full length of orange is missing. I do want to keep the colours consistent so it looked as though I was going to have to discard almost half the ball to get a match. Neither of the sections of yarn I had previously discarded included orange, which would have helped. Fortunately I have more of this yarn, and one of the balls starts with orange, so I am planning to take that and graft it in to the current yarn so my colours remain consistent, there will be a few more ends to sew in …
So the lesson from this is to allow a lot of extra yarn if you are using yarn with a long colour change.