I dunno, maybe they're less strict than I'm giving them credit for, I'm just assuming they wouldn't ever put a permit in the box if it expires that day. That seems like it would invite even well-intentioned visitors from ending up in a situation where they enter the next day.
Would be interesting to hear if they did allow this, because I would probably make use of it as well!
Even if not, it still means you could get in a half day at work, leave at lunch to get there before close, and be guaranteed a permit. Whereas before it wouldn't be worth driving up so late and risking no permit.
