Way to slow the elevator down

Just had one in my elevator and taking it wanted to go to floor -2 which was my second Imperial level. Not only did it give me coins, per usual, it also shaves a minute off any work being done on that level. For example, I was creating Security Codes and had 7 minutes left. After dropping the bitizen off there, a little -1 clock marker hops up on the top right of that level and reduces the time.

Also referenced and somewhat confirmed other people noticing this here: http://quickgamer.net/games/tiny-death-star/walkthrough/

Edit: Just confirmed again sending a ? mark bitizen reduces production on whatever floor it wants to go to by 1 minute.

Edit #2: Also verified that you can send it to any floor to get the time reduced even if it's not the one that it wants to go to. You won't get coins, but it still reduces the time by 1 minute.

Edit #3: Also side note, you can send any bitizen to an imperial floor to reduce the time by 1 minute at any point in the game.

Increasing PPM would have to lead to a higher passive credit earnings, as long as shops have stock to sale. The more people randomly delivered throughout the Tiny Death Star, the more people who buy items from shops.

How can we determine that PPM applies to passive credit earnings and not player activity? As there is no way that the level 2 elevator, the NB200 Commercial Lift, the first available upgrade for the elevator in Tiny Death Star, is generating 8 people per minute for the player to deliver. This rate means that the player would be present with a stream of bitizens spaced every 7.5 seconds after the delivery of the last bitizen.

Examining the second elevator upgrade, the Insta-Lift 2000 SE, we can see it has a 12 PPM rating. This means a bitizen would have to be popping up every 5 seconds in the lift to be escorted to a level by the player. So we can conclude that if the information posted in Tiny Death Star has any in-game meaning, then it must apply to the background bitizens that are arriving on the floors.

For further information, we can look at the Tiny Tower Wiki about elevators here: http://tinytowerwiki.com/Elevators
It notes that PPM = Passengers Per Minute, the rate that people are delivered. Since this rate is much too quick for passengers to be delivered by the player, it must apply to passive delivery (bitizens being delivered by the elevator "in the background").