I'm moved to ponder (which regulars will know is always dangerous, and new readers can discover for themselves by checking out posts tagged with 'thoughts' on here) by several threads and discussions here and there in the past couple of months on Big Games.
What do I mean by Big Games?
In this context, that moment down the club or wherever where you decide that you want to take a system you love on your usual 6'x4' table, and do something more epic on 8'x6' or 10'x6' or bigger, so you can get masses of figures on a table and Make It Look Totally Awesome...
And it never... quite... works. Moreso with some systems than others, granted, but...
It's kind of the inverse of the 'will <X> work with <Y> scale figures' question that you hear asked so often. (To which, in case anyone is still in doubt, the answer is YES OF COURSE, possibly given a little scale tweaking). Yes, games are often designed with a particular figure scale in mind, but... much more importantly, games are designed with a particular force size in mind. And in general, the rules will creak far more if you step outside the designer's idea of typical force size than they will figure size or table size. The latter are merely issues of ground scale, which you can fix with a calculator, spreadsheet, custom-marked ruler or swapping from cm to inches.
Admittedly, some work better than others: you can, for example, push most of the Warhammer-based systems (40K, Fantasy, WAB, Bolt Action) a bit more than you can, say, Chain of Command. Even so, though, you will get to the point where the granularity of the rules starts to break down in the face of more and more figures to move and interact.
So what do you do?
Actually, it hit me after a couple of comments from Rich on the TFL Yahoo! Group re large games of Chain of Command.
You're actually using the wrong rules to achieve what you want. If, for example you want a big, sprawling, company level WW2 game in 28mm on a 12'x6' table with a 1:1 figure scale? Don't use Chain of Command or Bolt Action, however much you might want to. Use IABSM/FoW/Battlegroup and nudge the ground scale up a bit. Think about it: you wouldn't generally use IABSM for a platoon level action, you'd use CoC or Bolt Action.
Just a (possibly controversial) thought.