He's not waiting any time really. The idea of his macro is

Use Heavy swing.
When heavy swing is used skull suffer sunder is placed on slot 2 on hotbar 1.
2.5 seconds later he will use the non macroed skull sunder.
1.5 seconds later Skull sunder will be replaced by Butchers block.
1 second later he will use Butchers block.
I could see where this could get messed up, but it's an interesting idea, but really risky if you run other macros.