The premise
The title says it: decision-making belongs at the center of goalkeeper practice design. The modern keeper defends space behind a high line, starts the attack with their feet, and makes constant reads — come or hold on a cross, spread or stay on a one-v-one, play short or go long under a press. A session that's only unopposed shot-stopping trains the hands and skips the brain, which is the same critique I'd make of any unopposed outfield drill.
How I'd design keeper training
Same philosophy as everywhere else for me — keep the decision in it. Instead of the keeper facing a line of shots, put them in a small game where they have to read whether to come for the through ball, where the pressure decides whether they play short or clear their lines. Unopposed handling has its place as a small technical dose, but the position is drowning in decisions, so most of the practice should make them read and choose. A keeper who can catch everything but reads nothing will still cost you games.