I assume some people use the 2.88 option to add custom images to the UBCD.
Many DOS programs are not compressed, or compressed with unefficient EXE compressors.
I normally use UNP.EXE by Ben Castricum to decompress them and WWPACK to compress EXE files.
COM files can sometimes be compressed converting them into EXE files first with BIN2EXE, then WWPACK them
SYS drivers can be compressed sometimes using PKLITE
Sometimes the compression breaks the program, you have to check for problems after compression. LZEXE is good too.
I hope to save someone some bytes with this tip
(WWPACK 3.05 gives me grief, I use an earlier version)