How to get four shipments per day without setting an alarm clock

I keep my game open overnight for just this reason. The problem is that even with the game open the reset timer sticks sometimes - sitting at 10s or 0s for 10-15 minutes. This happens every other day, roughly, shifting the timer over time. I've had the app open at the timer reset every time for quite a while and over the past week alone my timer has shifted a little over an hour.