Huh! I did not realize that QlikView would automatically convert a string literal into a time in that situation. It looks like it MUST match the default time format set in the script, but as long as it does, it properly interprets it. I just learned something new.
I'd probably still recommend against it because you might, say, go and change your default time format, and forget to change all your string literals. The approaches I used above are not sensitive to your defaults like that. Still, interesting.