As the title says, how do the virtual reels function when multiple paylines are in use? For example on a single payline machine the virtual reels could contain any symbols the physical reel has, jumbled in any order and the mapping of virtual to physical is only a matter of spinning until the virtual symbol is hit on the physical reel since what's above or below the payline doesn't matter.
What happens when multiple paylines are in use like triple top, middle, bottom, 9 lines or 20 lines in the later S2000 machines? A virtual reel could contain combinations of symbols like a cherry immediately followed by a triple-bar that don't exist on the physical reel: all cherries are followed by a single or double-bar.
Even if instead of a large virtual reel the developers used the physical reel with 'weights' on each symbol you could run into a situation where the jackpot symbols happen to be followed by cherries and single-bars (which have a comparatively much higher chance of coming up), leading to the situation where they pop up on the middle payline frequently causing the upper payline to hit jackpots at too high a rate.