It needs to work consistently for a solid month. If it works that long, it's a keeper. My current holy grails are Elucence s&c, Mastey Traite, Boots white stuff and Aura Hypo gel. Also, pure unrefined shea butter. My hair and skin love it.
When my hair was shorter (around waist length), my holy grails were Jessicurl Too Shea
and Rockin' Ringlets
. I had a loooot of good hair days with those two but my hair outgrew them.