Is there a way to get a game speed in between fast and slow mode?

I find fast mode too fast and slow mode too slow.  Or rather, slow mode is fine when the characters aren't stealthed, but I try to stealth them as often as possible.  Since fast mode is supposed to be double speed and slow mode is supposed to be half speed, shouldn't there be a "normal mode" in between them?  I feel like I've hit this normal mode once or twice and the characters move at the speed I want them to move, but then I accidentally hit one of the arrows instead of something else and I can't get back to this normal mode.  What do I have to do to get back to it?