As a single parent from the start, I absolutely agree with the guidelines as that is exactly how I felt in my gut with DS. Regular visits at my home by his dad when he was a baby, followed by short outings with his dad, followed by longer periods and whole days at his dads house. Even now he is nearly 3 and he spends the occasion night at his dads house I feel a little anxious - not at all because I don't trust his dad, he has a wonderful bond with him, but because I worry he will wake up not knowing where he is or be frightened. As someone who's been there done that I think the guidelines make sense with regards to supporting a sense if security and stability of a young baby/child. It's just how it felt natural to me and I didn't even read the guidelines until recently.
And using CS as a bargaining chip? Not acceptable and not the point of CS as others have said.