You want a separate password for screen unlocking. You may want this if ...

• ... you often lock your screen to go get a beverage, and return to your computer holding a beverage in your right hand. In this case, it may be convenient to have an unlock password you can easily type with just your left hand.

• ... you participate in video conferences, or may otherwise be filmed while typing your unlock password. Replicating password from video footage is easy unless you type faster than the video frame rate, but if your unlock password is different from your SSH password, it cannot be used for remote logins.

You don't want to press enter when you've finished typing your password. If your monitor is slow to turn on, you will never accidentally send your password as a chat message with this locking program.

You don't want to be penalized for typos by libpam, because you know that it's extremely unrealistic that anyone will successfully brute force attack your password with a keyboard.

You want to see for how long the screen has been locked, so that you can easily compare the time cost of various lunch strategies, and so that others can see for how long you've been away.

You want to see the clock without unlocking.