If you are reaching the shuttle a fraction late, the problem is almost never speed. It is the split step and the first push.
Most club players believe they lose rallies because they are slow. Video review tells a different story: they arrive late because the split step happens after the opponent's contact rather than a beat before it.
The six-corner drill isolates that timing. Start at base, split on the coach's racket movement, push to the called corner, play a shadow shot, and recover with a chasse rather than a run. Six corners, four rounds, ninety seconds of rest.
The correction to watch for is the first step. If it is a small shuffle instead of a hard push off the outside leg, you will always be half a step short on the deep backhand corner.
Run this twice a week for a month and the deep corners stop feeling like emergencies. Add a shuttle to the drill only once the timing is automatic — chasing a real shuttle hides bad mechanics.