Developing complex applications not only requires skilled programmers, it requires programmers who are familiar with the process and the tools they're expected to use. I'm a advocate that anyone working on a large application should at least be a CLD (Certified LabVIEW Developer), but I strongly recommend that they pursue becoming a CLA (Certified LabVIEW Architect). Unlike the CLD, which is a measure of someone's ability to write good code, the CLA assesses an individual's ability to design and, of course, architect an application.
This page defines the differences in the three levels of LabVIEW certification - note that certifications are available for a number of other NI products, including TestStand.
Both the CLA and the CLD are four hour exams. At the end of the CLD, you'll only need to submit a working and complete application that's well documented and reflects good coding practices. The CLA is divided been coding and short answer essay questions, which requires much more discipline when it comes to time management. One of the most notable and importance differences between the two exams is that the application you submit in the CLA is not required to be a working or complete piece of software. In fact, if you try to finish the application you'll almost certainly run out of time to answer the essay questions.
Also, try not to spill coffee all over yourself and the exam half-way through.... like me.
The code that you submit for the CLA should be a framework that clearly indicates what the sub-components are and shows your fundamental design choices, like how modules will communicate with each other, how application timing is enforced, and how errors are handled. Throughout the exam, I recommend a focus on providing just enough information for someone else to fill in the pieces, without spending too much time developing the pieces yourself (I kept having to remind myself throughout the exam, as I enjoy developing code and can easily get swept up in it). Of course, the code that you do write will still need to enforce code style guidelines and practices.
As for the short answer essays, I had many people recommend that I allot certain times to each section, but I instead chose to work on both at the same time. The essay questions ask about design choices and development practices you made and, in some cases, for justifications as to why, but they all apply to the code you're writing. I recommend reading the description of the application first, then skimming over the short answer questions so that you can be thinking about the answers as you develop your application framework. When all was said and done, I estimate that I spent just under half of my time on the essay questions, and the rest was alloted for coding.
In addition to justification of design choices, the short answer questions also cover a broad range of software engineering topics, many of which are covered in the Managing Software Engineering with LabVIEW and Advanced Application Architectures training classes. To brush up on these practices, or if you haven't taken the class, you can also review the material on ni.com/largeapps. Some of the fundamental questions will likely include topics such as team-based development and strategies for reuse. The full list of topics is available from the CLA Preparation Guide.
In addition to the resources provided by NI, which are available here, Darren has a popular blog entry on the topic that I found to be very helpful, read it here: LabVIEW Artisan.
One final note: If you get the certification and join the ranks of CLAs around the world, not only do you get a free t-shirt and the esteem of the title, we'll also look forward to seeing you at next year's LabVIEW Architect Summit here in sunny Austin, Texas!