This is a great discussion!
I agree that some proteins are stronger than others, but daily or even weekly use of even the milder protein treatments may result in an imbalance between the protein and moisture levels within the hair strands in some people. But honestly, its almost too hard to even go by the "types of proteins". You never know the
percent composition of these products so though it may have a specific protein down the ingredient list, it might not be as strong as if it were higher on the ingredient list(greater percent composition). The protein in question could be 30% of the product or 0.3%! Who knows! You have to play around with different products to know how strong it is on
your hair. You can't really say "Oh this is wheat protein so its gonna very light!" Or "this is animal protein, so its gonna be very heavy." It would be nice if that were true all the time, but because the product percent composition really plays such an important role, label reading can only do so much. For example, every product with keratin isn't going to feel the same way across the board. Just like every product that contains glycerine or water isn't going to feel the same! You must experiment and find your hair tolerance and it will vary from product to product, not necessarily protein to protein.
For example, some people think Aphogee 2 minute is a mild to tough protein, but my hair tends to laugh at it and feel the exact same after using it. For me, I just experimented using different combinations of products to find out what my hair tolerance is.
I totally agree that relaxed ladies need more protein. If you are relaxed or color treated, those processes have compromised the protein structure of your hair--so you kinda need the supplemental protein. Not everyone needs protein though, some naturals can live without it...
For the relaxed ladies though, It's like we've all sustained different degrees of "damage" from the relaxing processes. Some people's hair is more protein deficient by nature (from the coloring/relaxing) so they require more to keep the balance in tact. Relaxing and coloring breaks protein bonds so depending on the type and degree of relaxer and level on bond breakage you will need more or less protein than someone else. So you can't say weekly, daily, or monthly protein is too much or too little because we do not know the true condition and specific needs of your hair to start with. At the end of the day, you must experiment and get to know your own head of hair.