Thandi, in answer to your question, the protein treatment IMO has really helped my hair. It feels stronger and it left it soft& sheeny. I did condition with a moisturising condish afterwards. Hair needs the right balance between protein and moisture. Too much protein will leave it hard and brittle, while over conditioning will leave it limp , lifeless mushy. Personally I think our hair type is rarely over-conditioned. Still, striking the right balance between protein and moisture can be tricky. As a rule, too many protein treatments will lead to hard hair, At the same time you need them to strengthen your hair. So I suggest 1xmth at the most ,and always follow with a moisturising conditioner to be on the safe side. This of course, is a generalization and may vary from person to person. Adding a *moisturising*conditioner+humectants like honey,oils like jojoba,coconut& olive oils will help prevent "overproteinizing" your hair and don't forget finishing off with an ACV rinse!
Having said all the above, eggs, vinegar and oil are all great at helping retain moisture, provide volume and hydration. Each ingredient can be used alone but obviously a combination (as found in mayonnaise) increases the condish properties. The protein in the egg fill in the gaps and nicks in the hair shaft when it's dry or damaged, giving a fuller sheenier appearance promoting strong strands and growth.