@JCN-SBWD I think one clear link is good, but what's better is making the content useful to the reader.
If your content inspires, educates, or gives a quick win, readers are more likely to press a link to an external site (especially if it is part of your solution).
On top of this, you need to ensure your client's link and service/product offer aligns with the reader's needs, wants, and desires. I'm always amased at how often there is a disconnect here.
In terms of SEO, if you can create content that ranks well, then the traffic will be there... so it's more about how you prime your content to convert. I don't think we need to worry about link numbers in this case.