Those results sound about right to me. However, I am curious what level of compression you used for the Zip and 7Zip files. I just tested a graphics rich PDF and it appears Archiver treated it as a graphics file and did not compress the file at all. Zip, 7Zip, RAR, TAR/GZ all were the same regardless of the selected compression level or chosen algorithm.
Sorry, but your point is lost on me.
Keka, which I use for compression, doesn't specify levels of compression other than
like so, so the best I can do is say that I used the "Slow" setting.
This is interesting: My original 3.46 MB dmg was created by Disk Utility, but one just created by Keka was 2.86 MB...the same size as the DU dmg after 7Zip compression.
