Effective transaction security is not a single control. It is a layered architecture where each layer reinforces the others. A failure at one layer should be caught by the next.
Every additional security check adds latency. The question is not whether to add security controls, but where to apply friction and where to remove it. The core decision is whether to build fraud detection infrastructure in-house, integrate third-party services, or work with a development partner that builds security and compliance into the product from the start.