blank columns or separate tables

I have a form with 8 fields, 4 of which are required and 4 are not.
Usually if a field isn't required I would create a separate table for it
rather than having a blank value in the table where required values
would go. In this case, I'm not sure if I should put all the not
required fields in one table or separate tables. Since any one of them
can be or not be blank.

I'm trying to find a balance between normalization and practicality for
the database, as well as programming.

So, are columns with blank values acceptable to a certain number? Are 4
separate tables too many, so that there aren't any blanks in a column if
they were in one table?

Thanks,
Pasquale