Do engineers have to keep going back to school because their knowledge eventually becomes obsolete?

Question

If an engineer already has a degree I heard that their knowledge becomes obsolete after a while and they have to go back to school. If this is true, then how often do they have to go back to school and when they go back, how many units do they have to take? What % of what they learned when they first got their degree is still useful? I would assume that at least some basic things they learned is still useful.

Answer 1

In the US, many states require continuing education hours in order to renew your Professional Engineer license.  Typically 10 to 20 hours per year.

Answer 2

no, the only solution is specific training, if the company gives training on the specific topic he has to do for the company. he will recover soon

Answer 3

We don't go back to school.  But we get get Continuing Education:

Short courses

Seminars

Trade/Professional journals