Maybe @IntuitAustin can give you more information. I agree that the links and the information in them are inconsistent and often confusing, especially the release notes.

The main Thursday UPDATES are 3/05, 3/12, 3/19... The RELEASE dates are shown in https://proconnect.intuit.com/community/help-articles/help/2019-lacerte-release-dates/00/6538. A release is a whole new program and this is often where they break the program. The updates are for fine tuning and correcting release. Not every component and not every state is changed with either the Update or the Release. that is why you see so many dates. 

A critical update will show up as a red dot with a white X in the lower right corner of the program. 

I hate to try to defend what is frustrating you, but this is a very complex program, that is made in a very short period of time to keep up with idiot Congress and crazy Treasury Secretary changes that quickly evolve to screw the whole system up on an ever evolving schedule. I think Lacerte (and all the other tax software programs out there) are pedaling as fast as they can to get it right.