is it bad to apply Jamaican black castor oil everyday since that means I'll have to wash it everyday
I use JBCO (Jamaican Black Castor Oil) everyday as well. You don't have to wash your hair every day. It may cause buildup after about two weeks. That is the amount of time you should wait until you wash it. JBCO is to moisturize and oil your hair. Washing your hair daily only dries your hair up and makes the cuticle and root hard and brittle. This leads to dry hair and breakage. Try the LOC method as well, it keeps your hair moisturized for a week atleast. Do NOT was your hair daily. Just oil everyday as normal and after about 2 weeks you can wash. You will see great results. And also, I would suggest only to wash your hair with shampoo about once a month. It is very harsh on hair. Try to do a co-wash from now on. To keep everything smooth and nurished.
Your washing routine is totally up to your preferences :) Although I would not advise to wash it on daily base. Washing your 1 or 2 times a week is common but there is no specific amount, listen to your hair, if your scalp feels greasy then it's time to wash.
Co-washing is washing your hair with conditioner. Now there are products made specifically as co-washers or cleansing conditioners. Shea Moisture's Coconut & Hibiscus Co-Wash or Jessicurl's Cleansing Cream You can choose a product made for that, or a regular conditioner. Either way (like YourPoison said) co-washing is definitely a better way to keep your hair from drying out in between shampoo washes. I hope this helps :)