Highlights in hair...

6 weeks is about the norm before they need retouching

But it does depend on colours - I have copper and blond in my hair and the copper fades really quickly

It really depends on what you have done and on your natural colour but generally I think six weeks is a good result. My hair is dark blonde naturally and I have it highlighted to within an inch of its life so it looks very very blonde. As a result, by the time six weeks is up it is usually in dire need of redoing.

Meant to add, in what way do they look awful?