Consistency is one of the goals. That is why there is a person on set whose whole job it is to keep stuff consistent between takes.

Every time I see clothing/stance/water/sky change between shots it reminds me that I am watching a movie which in turn kills my immersion.

If you would take jaws the way it is and just change the inconsistencies it would be a better movie. Doesn’t mean it isn’t a good movie now.