Paying car insurance monthly does not help build credit.
But if you can only afford to pay your car insurance monthly then that's okay to do.
But if you can it's usually best to pay your car insurance yearly or at least every 6 months if your car insurance company allows that.
I pay my car insurance yearly in one payment as I save around $300.00 by doing so which makes it worth it.
I just put the money aside each month that I would be paying monthly to the car insurance company and then write the car insurance company a check each year when the car insurance becomes due.
Car insurance doesn't affect your credit score when paying monthly or yearly so it doesn't matter.