If the strategy needs to be changed, especially repeatedly, it means that none of these strategies are working. This is because there is no strategy that can manage random events. After all, then random events would cease to be random. So it's useless to look for a winning gambling strategy based on luck. A gambler's strategy may be to manage the bankroll in order to gamble responsibly. However, in some games where skill is required, or in sports betting, different strategies can be successful.
You are absolutely correct and this is very inline with what I said above, most strategies in gambling is simply to help us manage our bankroll better in order for us to remain as responsible gamblers.
And speaking of strategy in sports betting once again, even this strategy can not utter or change what happens in the field with the players, the what ever type of strategy we come up with, our winning will still totally depend on what happens in the field, what this simply mean in the end is that the strategy likely will be for us to still manage our bankroll better.
What ever strategy that can not utter or change the possible outcome of a game is simply a strategy towards bankroll management.