Here’s a useful hint. If you’re executing a command which is going to take a while, rather than minimising the terminal once you’ve started it, you can reduce the font by repeatedly pressing Cmd minus. That way you can leave the window somewhere visible on your desktop and keep glancing across to it. Your subconscious mind will usually let you know that it’s finished within a few minutes of the event, because it will pick up on the fact that the text has stopped moving.
Here’s an example Linux kernel compilation over ssh: