Every recruiter has heard it. The pipeline is too thin, send more CVs. It's the easiest thing to ask for, and almost never the actual fix, because a thin pipeline is usually a symptom, not the disease.
If forty CVs produced zero offers, the forty-first isn't statistically likely to be different. The filter is broken, not the volume. That filter might be the comp band, the JD's wishlist of eleven must-haves, or a hiring manager who can't articulate what a yes looks like.
Before I ask for more candidates, I ask for the last five rejections and why. Nine times out of ten, the pattern in those rejections tells me more than the next fifty CVs will.