Why should they have issues breaking 5 connections if they learned how
to break one?
5 is much too small a number to make that computationally harder. And
you cannot make as many connections to make it that hard so it does matters.
The attacks that I have in mind like end-to-end correlation attacks
should work either way.
These other Tor connections would also have to send dummy traffic.
Otherwise it would be clear which Tor connections are just idle and
which actually generate traffic.
Related:
https://forums.whonix.org/t/idea-proposal-of-a-fake-workstation