When you need it you need it, no matter how often.

in grad school we used it to share very powerful workstations without getting out of the office.

Sometimes I need to use a GUI program on my Desktop while I'm away. It might be something as silly as adjusting a parameter on a simulation run.

Sometimes I want to start a program on a remote computer (say VLC on my kids laptop downstairs)

Embarrassing admission - sometimes I know how to adjust a setting from the GUI and not from terminal. Maybe I want to mute a computer downstairs (btw, just an example. I'd use alsamixer, if killall weren't an option).

Honestly, I'd use it a lot more if it were faster and less laggy. Daily, even.