I totally agree with setting goals, not only for hunting, but with anything that is important to you.
In fact, I'm not sure what hunting would be like with no goals? Do you just shoot anything that walks by, or decide when you see it, whatever it may be?
Nothing wrong with changing your mind about a goal, even on the fly, but I set goals for the season, as well as each day hunting. Ask my kids - "what is our first goal for the day"? "go home safe dad"!