Teri actually advised in her book not to use leave in conditioners and just use regular conditioner instead because leave ins are often too watery/light or contains ingredients that make the hair feel sticky, etc.
Teri also mentioned in her book that deep conditioning is unnecessary because deep conditioners usually contain the same ingredients as regular conditioners.
I agree that everyone'e hair is different and what works for one person may not work for another, but I think keeping it simple is best for growing natural hair long. I have been co washing and leaving conditioner in my hair since 2007 and my hair is now tailbone length. I started out at bra strap length with shoulder length as my shortest length. After growing out from shouder length I was stuck at bra strap. I only had waist length hair once during my early teen years. This is the longest my hair has ever been in my life.
I think for most natural hair, all that is needed is conditioner and perhaps a little oil such as Extra Virgin Olive Oil at times. I also finger comb and never deep condition either.
I have Teri's book and I love how simple and practical her regimen is. Even her hairstyles don't require a lot of skill.