How long should parents spend with their children's

In truth I am not entirely sure what you mean .... '...with their children's' WHAT?

Or do you mean 'with their children' in terms of parents spending time with them?

If it is the second answer, then depends on age.

You need to form a much better question .... or no one can answer you.

Welcome to posts by folks who are (likely) Chinese.

The 's is probably intended to be a plural (and the poster may not know that children is a plural term). Hence the question is probably How long should parents spend with their children?

Still unclear but a bit less.

And then, given the adjective "long" with the verb "spend," I hazard that the OP means to say "How much time should parents spend with their children?"

Is that the case, AlbertoYao?

I would say - As long as possible.

Isn't that the purpose to 'having' children, Perhaps?

Mark