It's a fine line isn't it? For me, it's always about trusing my instinct. With no VE to tell me what the cervix is doing I look at mama's face. If there is a deep satisfaction look there then my gut tells me it's okay. If I read something else then a VE might be called for. It's hard to be completely hands off in every birth, isn't it?
Here's a link to a recent discussion we had about this;
There is a voice inside of you
That whispers all day long,
"I feel this is right for me,
I know that this is wrong."
No teacher, preacher, parent, friend
Or wise man can decide
What's right for you--just listen to
The voice that speaks inside."
— Shel Silverstein