When we did the "Bible Studies" I quickly realised that the opening and closing prayers were conducted by the study giver, or her husband when he came along (I didn't realise the rampant sexism then). There was a lot of "Jehovah" this and that, as if God needed to be reminded of his name, and I was allowed to say "amen" at the end.
I learned to keep quiet till she was done, and then not say "amen". When she asked about that I explained that prayer is personal, and I preferred to keep it that way. Probably another reason why I'm "bad association". But really, it is the height of rudeness to impose your conversation with a (real or imaginary) God on others to teach them what you think are the correct forms.