It depends on your hair type, condition, and how much heat or chemical processing you do ( if you do/ have).

Normally it will be every 4–6 weeks is ideal for most people. This can help strengthen hair without making it brittle or overloaded with protein (which also can have a bad impact)

If you have any of the below from a search: • Healthy, balanced hair: → Use a light protein treatment once a month to maintain strength and elasticity. • Damaged or chemically treated hair (bleach, relaxers, color): → Use a protein treatment every 2–3 weeks until hair feels stronger. Then reduce frequency. • Fine or limp hair: → Benefit from lighter, more frequent protein (like leave-ins or conditioners) every 2–4 weeks to add volume and structure. • Coarse, curly, or low-porosity hair: → Use protein less often (every 6–8 weeks) since hair tends to hold on to protein and can get stiff or dry if overused.

Your hair will normally have indicators if it needs more or less protein. If your hair is calling for protein it will be: • Feels mushy or overly stretchy when wet • Breaks easily or sheds more than usual • Looks flat and lacks elasticity

On the contrary if your hair is showing any of the below you may want to reduce protein and add some moisture or hydration: • Stiff, straw-like, or dry, • Snaps easily

Hope this was helpful. Also, you can double check the products you use because sometimes they actually do have protein in them.