Class in session - have a seat.
... the bigger the spark in the cylinder which equals more power, more complete fuel burn, and less chance of fouling a plug (as long as the plug is the correct hear range)
I'll back that up. Small gaps are not
where it's at for performance. Quick outline - there are two ends of the spectrum on gaps, small and large. Small gaps used to be the mechanic's trick to help a tune and set of plugs last longer, starting back when all you could get was 'standard' plugs that eroded relatively quickly, and plug changes were recommended at 15-20,000 mile intervals or less and plug wires broke-down more quickly. The other end is the performance view, which assumes you are changing plugs and other ignition system parts whenever necessary to maintain the largest spark you can for power and efficiency. Factory settings are in-between these two.
For best performance and efficiency, you want the largest, hottest, and longest duration spark you can get. That means the biggest gap you can run reliably. How do you figure-out what gap that is? Simple testing. There are two primary limits to the gap you can run - compressive resistance and coil energy.
Dynamic cylinder compression increases the resistance of the gap the spark must arc. Air is an insulator, and if you pack more of it into the same space by compressing it, the insulation level rises and becomes harder for the spark to jump. Coil energy in a single coil system reduces as RPMs rise due to reducing coil dwell, the time the coil has to charge between firings. There simply isn't enough time for a single coil to fully saturate (charge) on a V8 at high RPMs, and so coil energy reduces. This is why multi-coil distributor-less ignition has become popular, as each coil fires much less often at the same RPM and has plenty of time to charge between firings (coil dwell).
So, misfires due to resistance and lower energy begin to appear at WOT low RPM through peak torque where dynamic compression is greatest, or higher RPM where DC is falling but coil energy is falling-off quickly—or both. To find your best gap, start big and reduce it until you have no more misfires anywhere in your WOT RPM range. This job is easy and accurate on a dyno, as you can see the misfires on the traces. A bit more effort and less accurate on the street or track, but obviously simple and do-able. Remember—as the gap gets harder to jump, and if the rest of your parts (wires, cap, and rotor) are not in good shape, the spark will go the easiest path, and cause misfires when they jump to a close wire or cap terminal (a cylinder with less compressive resistance) or a convenient ground like the block, valve covers, or headers.
Wait - why did Paul say the smallest at idle then? Actually, that is an old tuner's track-side trick. When you don't have the opportunity to test for best gap, and you need to get the car on the track with the best chance that you won't have compressive or dwell misfires, you can do it that way until you get the chance to do it right - which takes time. Most hobby folks don't want to pay a mechanic extra for thorough testing, and they want to avoid a tune-up as long as possible, and so they get the 'little gap' trick. Yes, the tune will last longer, but no, the power and efficiency won't be peak. It's your choice.