I recently sat for the CLAD (in Sept 2018) after about 2 days of studying. I would say that the online samples you can find are NOT very similar to what I received. The online samples test a good amount of simple knowledge questions, and you either know or don't know, and get ample time remaining after you finish.
My actual CLAD had mostly "which of these will do what you want" with basically 4 or so diagrams for you to evaluate under time pressure. Which is way worse than "what is the output of this block diagram?" because you have to go through 4 or so of them. In some ways, you needed to know far less about terminology and such, but have to be way more able to use your brain as a CPU and crunch code through it. However, they were less tricky or knowledge-intensive than the Daily CLAD questions.
Not complaining since I passed with just one mistake, but for those prepping out there trying to memorize lots of terminology about architecture and such, that might not be the best strategy (but this is just n=1)... I do fear the CLD though... Really not prepared or good enough at Labview to have a sudden career change into a LV engineer...
Thanks for sharing your experience. As for the CLD, I think it is valuable whether you are a physicist, engineer, technician, student... Either way, studying for the exam is going to help you write better code (for the most part). Some of the things that NI wants to see, like wrapping every single SubVI in an error structure, is not something I personally think is best practice, but for the exam you just go with it.
I have never been a full-time "LabVIEW Engineer" but I still find the certifications useful for the knowledge they require, and for access to certain discussions like CLD or CLA summits.
For me, there was a bit of a life situation that forced my hand... But if I'm going to do it, I intend to go all the way. It might take a few years (or more), but attempt up to CLA/CLED/CTA. Just a bit behind since I never did comp sci seriously (though OOP and more advanced stuff I probably won't need till much later, and hopefully I can pick it up.) Also wish I had done some basic mech e and EE stuff (mech design, cad work, analog and digital circuits, high speed circuits, microcontrollers, etc.) earlier in life since they would be very useful right now...