An example of how the game can provide unexpected results, while behaving exactly as programmed:
Eastern Canada has 100,000 supplies on 12-7-41, and receives 1,000 supplies each day. I'm with replacements and base expansion off by default, so nothing is consumed there. So in 12-8-41 it should have at 101,000 supplies, less what was transferred or used, right? Unexpectedly it has 102,806 supplies - an excess of 1,806.
I was left scratching my head, until I noticed that it has one unit (RCAF Canada Base Force) with 2,000 supplies on 12-7-41, when it requires only 178 supplies. So the game smartly left 188 supplies on that unit on 12-8-41, and repossessed 1,812 supplies back to the base; with the 1,000 daily allowance, and less 6 for local consumption (or whatever), the math fits exactly at 100,000 + 1,812 - 6 + 1,000 = 102,806.
The whole mechanism is quite nice and very smart. Kudos to the programming team to going to these details.