One of the lessons any adult learns upon re-entering the education system is that, colloquially speaking, you use it or lose it. This often becomes painfully clear when attempting to work algebra equations. This can also apply to grammar and English composition skills. Humans become very good at the things they practice, and grow worse at the things they do not practice. A working professional who cannot handle basic math and English is only as professional as the last skill he or she employed. For example, consider a sales professional who uses poor grammar when responding to a sales order via email. His or her skill in person is without question, however, judgement on poor grammar can slant the customer's view of the person.
A person should never be satisfied with what they have learned. Ongoing learning, training, and education is essential to meeting the demands of the world. This doesn't mean that a person should partake in formal education, just that they should continue seeking out new knowledge and techniques to stay relevant in their field.
Sadly, the basics like cursive writing and general math done long hand have been eliminated from our children's curriculum. I have had 20 and 30-year olds come into the tax office and can't even sign their name on a OFFICIAL FEDERAL DOCUMENT with a written signature! And they don't even realize that it's required for that type of document! Car titles, checks, anything that must be notarized, etc. ALL require a cursive signature.
It is the responsibility of the individual to make sure they retain the information they learned in grade school and college. The education system is already a large burden on the United States budget, so spending more money just to make sure they retained the information is a waste. Also, there are adult training programs if a person really needs to learn something again that they may have forgotten.