Bats DO go dead. Age is not the culprit but the metal fatigue caused by the ball contacting the bat and the subsequent flexing of the bat. I have heard it said the life of an aluminum bat is about 250 hits. A good high school power hitter will average about two bats per year. In college my son would go through 3-4 bats per season and this is using wood in practice. He practiced with wood during high school and college. If a player uses aluminum in practice he might want to consider a “game” bat and a “practice” bat.
PS: Let me add that by using wood during practice the players will subconsciously turn an aluminum bat to “trademark up” hitting the ball in one area creating a premature flat spot on the aluminum bat.