I think you are using nonstandard language. Tactics are short term material wins. Hanging a piece is absolutely tactics, it's a one-move tactic.
You seem to be saying that "defending against tactics" is strategy, which I guess it is, but it's a very tiny strategy that won't fill a "study". Once you know the idea of "find your opponent's best move before you choose your move". There's no more of the strategy to study , you just apply the tactic every turn.
Things like maintaining control of many squares, building a >3-move plan around depriving the opponent's bishop of mobility, and switching between these plans when they are inevitably interrupted, is strategy that takes a lot of time to study.
You seem to be saying that "defending against tactics" is strategy, which I guess it is, but it's a very tiny strategy that won't fill a "study". Once you know the idea of "find your opponent's best move before you choose your move". There's no more of the strategy to study , you just apply the tactic every turn.
Things like maintaining control of many squares, building a >3-move plan around depriving the opponent's bishop of mobility, and switching between these plans when they are inevitably interrupted, is strategy that takes a lot of time to study.