Memory is fallible, and routines can change for convenience or on a whim. Using a static, printed checklist ensures that every item is completed, every time. Checklists are routines that have been optimized by time and experience. Do exactly this, not something else, and you are most likely to get back on the ground safely.
When we trade on whims or even our own studied hypotheses, we are going out on a limb, straying from what has been proven to work. The odds are low that a string of such deviations will bring a superior result.
Just because something has been done before and is thoroughly defined, doesn’t mean it is boring and unexceptional. Thousands of men learn to fly fighter jets each year, and they all follow checklists.