I think that's what confuses people. Motorola cranks out new builds quite often. The thing is, only a fractional number of the builds that are compiled ever actually make it to Verizon for testing. Most don't even make it outside of Motorola. Some builds are badly broken, others are to test one specific fix.
What people fail to realize is everytime the source is compiled, it results in a new build. I firmly believe that the appearance of a build on the "Cheesecake" servers has nothing to do with how far along it is in testing. Just that it made it far enough through Motorola's testing that they are testing OTA functionality. Think of it this way: If I have an OS which I compile with build number 1.0.0.0; and I notice the word "Menu" is misspelled. I recompile to fix just that one little issue. The resulting build is no longer 1.0.0.0; it would need to be incremented (i.e. 1.0.0.1)
In other words, just because this build in on MOTOROLA'S servers, doesn't necessarily mean that VZW has even seen it, yet. Once VZW gets ahold of it, they need to put it through their multiple stage testing process.
I believe that the GSM models actually have solid release dates simply because Motorola handles the updates for those phones, rather than the carrier. The LTE devices, on the other hand, have no solid release date because that is 100% up to the carrier, and US carriers do NOT like to give release dates.
