If I were addressing my earthly father, I would not ever call him by his personal name. I would know it, respect it, and have deep regard for the importance of it to my earthly father. But I would never use it in personal address.
Same here. I have a closer relationship to God now, than I ever did before in my life. When I pray, I say "Heavenly Father". I remember the one time I called my dad by his first name. I was quickly shut down from doing that again. LOL! Honestly, I think it's disrespectful for a child to do that.