This feature (multiplexing SSH channels between same pair of machines
over a single SSH connection) is pretty cool. I have been using it for
quite some time and happy with the speed-up in connection setup time.

Though why isnt it done by default? Most of the users are unaware, as
this requires additional configuration, and thus missing out on it.

I have only read advantages of ssh connection sharing, and curious to
know if there is another side of it, due to which it isnt the default
setting.

Thanks & Regards,
Asmita