I saw this question, but mine is slightly different.
Could a hyper militaristic society get better soldiers by training all children from when they are toddlers?
They would be put in state-run training centers, where they would be rigorously instructed in combat skills. While they would probably not be strong enough to hold and fire adult sized assault rifles, they could still be taught how to dig defensive fighting positions and reinforce them with wood/sandbags/scrap metal, clean and maintain weapons, perform first aid, to practice proper gun safety, to swim and climb, the basics of hand to hand combat, map reading and navigation, vehicle maintenance, etc.
They could start with simpler tasks first, then move on to more complex ones later. The children could also be taken on long marches through harsh terrain while carrying heavy weights to toughen them up, and made to play "anything goes" capture the flag to increase their aggression.
Electric shocks would be used to make them follow orders and to become very disciplined and pain resistant. You would also be able to control their food, water, and sleep schedules, so that you can teach them how to operate while starved, dehydrated, and with little sleep.
You would also be able to indoctrinate them about the glory of the state and to exterminate its enemies without mercy, because they are disgusting subhuman vermin.
Obviously, these children would become emotionally-stunted borderline-psychopaths, but would this process result in improved soldiers?