Is it common? No. Is it unusual? No. Is it down to the individual dojo/system/teacher? Yep. If you have an issue with it, talk to the instructor. Ask them their reasons for using it.
That said... I don't know of any JAPANESE Jujutsu systems that use such methods for ranking. Then again, I don't know of any JAPANESE "Jujitsu" systems... for the record...what is the actual art you're training in? Which system? If I'm right, it might go a fair way to explaining why the training method is the way it is.
(Just because I was asked, and because I think it might have been missed initially)
For clarification, my comments about no Japanese "jujitsu" systems wasn't an attack on spelling... it was an observation of a few telling signs in the OP which indicated to me the likelihood that, in reality, the OP is not actually training in a Japanese Jujutsu system... but instead in a modern, most likely Western (but influenced or based in something Japanese, or Japanese based, likely Judo or similar) system. The idea of army crawls are far more likely there, any major focus on anything to do with ground fighting is not really common in Japanese systems, and is more a modern Western approach (influenced by BJJ and Judo), and so on. As a result, my comments were to try to ascertain where the OP was training, as the original question was "is this common in Japanese Jujitsu"... and, bluntly, the answer is no. Modern, eclectic, Western systems? Yes, although not necessarily as part of a grading.
To that end, I ask again to the OP... What exactly is the system you're training in? Without knowing which art/system, it's hard to say if something is common, unusual, or bizarre. And, to be absolutely clear here, there is nothing wrong, substandard, or bad about learning a modern, Western approach... in fact, depending on the context you're training for, it could very easily be better suited than an actual Japanese system... but asking in the context of Japanese systems when it seems you're not really training in one seems a bit less than relevant.