For me, my high bar that I have yet to beat, was the time I pivoted the running OS (ubuntu) into RAM over SSH so I could unmount and image the boot drive without rebooting and loading a live USB (Which would have required a ticket with my provider to enable IPMI)
Using dd to move-resize a partition by writing down the cylinder numbers and moving it piece by piece like some Tower of Hanoi. Wanted to add more space to my root after deleting the Windows partition, which happened to be first. There is apparently no built-in command to do that.
Booted up fingers crossed and everything worked.
I always liveboot debian and just use Gparted, faster than figuring out the commands manually, and much less risky