What an NDA really does
The value of an NDA is mostly realised before anything goes wrong. Signing one turns a vague sense of discretion into defined obligations: what counts as confidential, what the recipient may use it for, who inside its organisation may see it, what happens to the material when talks end. People and organisations handle information more carefully when they have signed for it. The document creates accountability, and accountability creates discipline.
Legally, the NDA gives you a contractual claim you would otherwise have to build from statutory fragments: the unfair-competition rules on trade and manufacturing secrecy (Art. 6 UCA), general liability, and whatever else fits. With a contract the questions become simpler. Was this information covered, was it disclosed or misused, what does the agreement say happens next.
A well-drafted NDA is also the natural home for a contractual penalty (Art. 160 CO), which relieves you of proving the amount of your loss. Under Swiss law that is usually the hardest part of a confidentiality case.
Where NDAs fall short
Be honest about the limits.
Detection comes first: you often never learn that your information leaked, or you learn it long after the damage is done. Then proof. Even when a competitor suddenly knows your pricing, showing that this knowledge came from your counterparty rather than elsewhere is genuinely difficult. And remedies arrive slowly. Damages compensate, they do not un-disclose, and by the time a court has ruled the information may have lost its value.