I find the sustained lead very difficult. I started that way and I became a decent shot, but I learned a different technique that is much easier for me.

I prefer to blot out the bird. By that, I start from behind, catch up and slap the trigger as the bead touches the bird - dust - gun is moving quite fast and I like to shoot them really close to the trap. Every angle, every (almost) time. Dropping birds same. The proper lead just seems to happen. That's about as good as I can explain it.
Oh - with the flintlock, I have to pass the bird by a foot to 18", due to the slower ignition and shot cloud, from my 20 bore.