Question on Matryoshka extraction mode

[gcarmix]

I have a qustion on binwalk usage on the Matryoshka extraction mode: when I extract files from any compressed format i noticed that these extracted files often will not get listed in the analysis even if they are a recognized format, for example ELF files.
But if I take the single extracted ELF file and pass it to binwalk, it will be analyzed and reported. Instead if the extracted file is another compressed format then it will be analyzed correctly by Matryoshka. What is the rationale with this behaviour?
Is it just a way to reduce the analysis time in Matryoshka mode?

Thank you