I'm thoroughly confused about when LNF is necessary and/or appropriate. I've asked questions in a thread and gotten answers I don't understand, and I see other threads where other people are confused as well. The FAQ on the Marriott site don't seem to answer these either.

Do all rooms booked directly on the Marriott site qualify for nights and points credit?

If I need to put some rate code in, or Marriott or some other site puts it in for me, but I am booking on Marriott.com, do I need to do LNF? How do I know when I need to ask for LNF?

It's Marriott's program, and they can run it any way they want, but people have said I need to do two separate reservations on the Marriott site to get credit for stays with a rate code, and that just seems pointless to me.

I appreciate the others who have tried to answer, but an official reply would go a long way to clarifying this for everyone. Thanks.