When you want to get a color, it’s always a trade off between what is hot and on trend as well as high Maintainence right? After all no one wants a color they need to redo every few weeks, that’s just not practical or cool!
The trick is using multiple tones to add the overall color, the use of varies shades adds depth and texture ( possibly the most over used word ). If it’s highlights you are looking for then using two different colours it changes the way it looks dramatically but yet keeps it low Maintainence. If you go for one color, chances are with less variation the natural hair will be visible faster.
With balayage you are best to keep it to one color and don’t go as light, it looks best when it’s more natural and as if it’s happened over time in the sun. Don’t get fooled by thinking more is better, less is best when colouring your hair typically.