Keeping my head on the stock, and my eyes on the target works pretty well, I've found.......many, many times.
Too much analysis of our given eye-hand coordination can short-circuit the process.
Rarely do two individuals see properly led targets/birds exactly alike. FWlittleIW, I probably use sust. lead most in the field. I probably take at least 25% of my woodcock on the way down using sustained - b/c they've stopped juking by then. For stuff over 40 yds I use alot of unmounted gun speed with pull away, or a queer variation where I look way ahead immediately before triggering. If there's one bird I tend to shoot swing-through, its grouse. Just can't ever seem to start in front of them. And I never use a diminishing lead technique on anything. I'm not smart enough to learn how, I suspect.
I'm with those who use a farther hold point and a more compressed swing when using a lightweight. Nothing chews me up worse than trying to execute a roundhouse swing with a light gun. One of the biggest errors I could make with a light gun is to think I ought to take targets quicker b/c the gun is lighter. The reverse is more like it. I don't particularly enjoy shooting my tube sets, but I hit targets alot faster with them. As others have noted, light guns require more finesse (read as "corrections"). This translates as a need for greater elapsed time from seeing bird to being ready to trigger a shot. Well, for me, anyway.
Sam