Back in post 48 (not numbered) I described cloning an SD card using rpi-clone. One of the problems I moaned about at that time was that the SSH session timed out part way through the lengthy copying process. This forced me to sit there while my 2nd try ran. I should have Googled "raspberry pi terminal timeout". As usual, there is a messy file in /etc cover this problem -- namely /etc/ssh/sshd_config.
And if you:
sudo nano /etc/ssh/sshd_config
And strangely change the line:
Then your SSH session won't time out. Hopefully.