If one more coat covers it to your satisfaction, that's all that's needed. Even though the first coat is your prime coat, so to speak, it's over an existing enamel so the durability and beauty will be there with two coats.

You only need to wait 16 hours when priming over bare wood.
Six to eight is sufficient recoat time.

Michael

Thanks, Michael. You've been so helpful and your long directions were great!