The time will vary greatly depending on the type of project and the verification techniques employed. In general, the idea of scope verification is to compare the requirements to the product.
I can give you an industry specific example. In software development, scope verification is usually coupled with quality assurance and testing. So there is unit testing by the developer, system testing by the test team, and depending on the requirements, there may also be load and stress testing. As a rule of thumb for software development projects, I look at coding as being as little as 5% of the project if there is good planning, requirements, and design. In reality it may approach 20-25%. If a full testing regimine is required, that may be another 20% of the overall project time. Project management is around another 10% of the total.
In construction (let's look at a typical residence), the scope verification is usually performed at move in time. There are quality checks along the way, then a series of final inspections and punch lists.