worker’s occupational knowledge

It means that all the knowledge (training, education) that a worker has becomes obsolete (no longer useable) because of the increase in automation used for that job. So every 5 years, workers need to update their skills and education and learn how to use recent technology.

BUT . . .your quoted paragraph is not well written. The first sentence does not make sense. I think is should be:

The amount of time it takes for a worker’s occupational knowledge and skills to become obsolete has been ACCELERATED (speeded up) because of the introduction . . .

Still confused.

let me break it down ...

>>The amount of time it takes for most of a worker’s occupational knowledge and skills to become obsolete has been declining.

so, For example, if earlier it takes 5 years to obsolate, now it takes say 3 years ....its declining.

>>>because of the introduction of advanced manufacturing technology (AMT)

Why ? how the automation can reduce the skill obsolate time ? if automation is used we learn new skills . we forget the old skills.
So, "a worker’s occupational knowledge and skills to become obsolete has been declining".....is not meaningful because we reject the old skills .

declining is a bad word ,I think .

Am I missing something here ?

Maybe you are over analyzing it. It is saying that technology is rapidly advancing, so instead of running the same equipment for many years, companies are continuously investing in new equipment or controls. That is the AMT part. Since this equipment is changing so quickly, workers must learn how to use the new equipment. It is not that the old skills are forgotten, just that they are no longer pertinent because that equipment has been removed. The time is dropping because businesses are updating their equipment more often as the rate of technological advancement increases.

and a worker who doesn't keep up his knowledge by learning the new skills finds himself out of a job sooner than before.