Impact of defining VARCHAR2 column with greater length

Question

What are the effects of defining a column with VARCHAR2(1000) instead of VARCHAR2(10) in Oracle, when the values are not longer than 10 Byte?

Answer 1

In the database, there is no difference. VARCHAR2 are stored with variable length, the declared length is only a limitation.

However, some client applications will reserve 1000 bytes per column instead of 10 if they see that the column is defined as VARCHAR2(1000)