I take biotin 1000mcg, cod liver oil, and folic acid once a day, how often should i be taking collagen?

Depends on use?: Your biotin will help hair, nails, skin, and cod liver oil will help myelination of nerves, and folic acid depends on if you are MTHFR variant that may not absorb this well affecting demethylation pathways. Collagen is great for joints, gut repair, skin, hair, nails too, and perhaps better than glucosamine or chondroitin for joints. It's the building block for connective tissue. Daily is okay!