> practicing batting and then practicing golfing and then practicing kendo swings
Actually, as the subject progresses toward being an "expert" their practice should be increasingly specific. Beginners will certainly benefit from the approach you mention initially, but professionals will not.
Regular successful achievement of a physical task (reliably hitting a ball with a bat) can be considered a walk through a problem space. Initially, any training that approximates the task will take you closer to the target in the space. However as you approach that target, the margin for error diminishes sharply. Consequently your training should become more specific.
> practicing batting and then practicing golfing and then practicing kendo swings
Actually, as the subject progresses toward being an "expert" their practice should be increasingly specific. Beginners will certainly benefit from the approach you mention initially, but professionals will not.
Regular successful achievement of a physical task (reliably hitting a ball with a bat) can be considered a walk through a problem space. Initially, any training that approximates the task will take you closer to the target in the space. However as you approach that target, the margin for error diminishes sharply. Consequently your training should become more specific.