Don’t overly stress or excessively study about the deck general module.
I took Master Inland Any Gross Tons along with four other endorsements about 10 years ago. I had to take 5 deck general modules. Some were harder than others. I breeze through all five endorsements in 3-1/2 days. The only thing I studied was rules of the road. The only thing I flunked was the Celestial module for a license with an oceans endorsement. I had to study hard before retaking that.
The Master Inland AGT exam, including deck general, was ridiculously easy. Perhaps on par with the AB exam.
I’ve never taken Master 1600 Inland, but I would expect it to be super easy for anyone with a few years of experience.
Rules of the Road is the most important thing to study for because you need to know it cold, including the right way to read and answer tricky and awkward USCG questions. At 90%, there isn’t much room for error.
Near Coastal and Oceans Terrestrial and Celestial are the most difficult modules with a lot of concepts and methods to learn, and a lot of opportunities to make math or tables errors. Again, these are 90% modules with not much room for error.
No need to worry about Terrestrial or Celestial if your sitting for and Inland license. You don’t need to know it.