As a consultant in the area of computer system validation, you see a lot of different approaches to computerized system and software validation. The real trick to a good CSV approach is to mix in some planning and a little common sense. The goal is to have a high degree of confidence that the system will perform its function in a manner consistent with its intended use. This is also scaled to reflect the potential impacts of failure. If the impact is that there is some inconvenience or business effect, that is clearly different than if the result would be harm to a person or persons.
Another issue that you run into as a consultant is that you may be brought in right at the beginning, or, maybe more often, in the middle or the end of a project. You also come across clients with various levels of expertise.
In general, the earlier you get into a project, as a consultant, the more you can affect the outcome. If you can help get user requirements in place that are realistic, testable, and are actually required, that alone can save a ton of project costs compared to an un-necessarily detailed boiler plate that you will later regret having to test to. Similarly, risk assessments can be focused or can get out of control and take up a lot of time and money that most small to mid-sized companies could better spend in other areas.
For this short post I will mention one other thing, which is to consider the life cycle of the system and how it will be supported. Zoom out to see what, strategically, best serves the purpose once the system is implemented. Can you do something for a reasonable cost and timeframe that will get you to the next level, where you will have more information, and make an adjustment to meet the future demands? Or should you invest a ton of time and money into something that you might need if you become wildly successful. R&D money is usually tight, and when you can save it, and time, with some planning and good decision making, that is usually a plus for your ability to grow even bigger in the future.
So please, think about and document what you need in that URS, put a solid validation around the system, and put procedures in place to support your new validated system and help fill any gaps. Then, when that system is past its useful life, you can repeat all that with an even better system!