I started using protein in products.... PT's first then in RO's and finally LI's. I do a wet-scrunch test:
Mushy hair and loose waves when released = needs more protein
Hair has some structure to it and holds a tight wave/curl when released = just right
Hair feels hard and resists scrunching = too much protein, do a DT
It took several weeks of slowly upping the protein before my hair stopped feeling mushy when I wet-scrunched and started having decent wave when dry. Also, the terms protein-sensitive and -craving are misleading, protein requirements vary along a spectrum just like moisture, some people need less and others more. The trick is to find you're hairs happy place and try to stay in it.