Large files / sets of files with 7zip means you can use all files as a dictionary for the compression. (across-file compression, called "solid compression")
However, zip does not supports solid compression. Which creates the oddity of zip'ing twice can reduce your file size because multiple duplicate files may have the same compression but they are stored separately (and the second pass then notices the similarity).
The downside of solid compression is you have to extract any files related to that block. But with modern computers that's not as bad as it used to be, and modern 7zip doesn't extract "all" files, only the ones affected by that block.
However, zip does not supports solid compression. Which creates the oddity of zip'ing twice can reduce your file size because multiple duplicate files may have the same compression but they are stored separately (and the second pass then notices the similarity).
The downside of solid compression is you have to extract any files related to that block. But with modern computers that's not as bad as it used to be, and modern 7zip doesn't extract "all" files, only the ones affected by that block.