Why would it be better for an engine to use less than the maximum time it has available per move?
Because in competitive chess games, the time limit is usually 40 moves in 90 minutes. You don't have a fixed amount of time per move. It's up to you how you want to spend that time budget.
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Because in competitive chess games, the time limit is usually 40 moves in 90 minutes. You don't have a fixed amount of time per move. It's up to you how you want to spend that time budget.