Blonde highlights chemically lighten specific portions of your hair to give your hair a more dimensional and vibrant look. The frequency of the highlights depends on a number of factors.
You should never get blonde highlights if your hair is already heavily damaged. If your hair is very frizzy, dry, breaks easily or has been colored a number of times, highlighting will make the damage worse. It is better to grow out natural hair and wait until it has recovered before getting highlights.
If the blonde highlights are closely matched to the natural color of your hair, the frequency is low. These can grow out and match the shade of your roots closely enough that you do not need touch-ups that often. The frequency of these highlights is around three months.
Short haircuts often do not need to be bleached to be highlighted. The chemicals can simply be painted on the hair itself. This type of highlight may wash out or fade over time, so get it touched up when you go in for a haircut. This is usually every eight weeks.
Natural blondes should not get highlights too often because their hair naturally lightens with the sun. The radiation from the sun will affect the color of the highlights as well. Every two to three months is acceptable.
If you have blonde highlights and your hair is naturally dark, get them redone every six weeks. The dark regrowth is very noticeable, and the highlights themselves can appear yellow with time.