Glue or Not Glue soft spine to book block

I primarily make case bound, hard spine journals. I do not glue the spine of the book block to the hard spine of the cover. Only the mull and endpapers.
What is the convention for when the book cover spine is soft and rounded? I am repairing a soft rounded spine book and need advice.
thank you.
What is the convention for when the book cover spine is soft and rounded? I am repairing a soft rounded spine book and need advice.
thank you.