Coffin Texts - Ancient Egypt?

Question:Why were the texts painted on the insides of the coffins rather than inscribed on the walls of the tombs?

Best Answer - Chosen by Asker: Why were the texts painted on the insides of the coffins rather than inscribed on the walls of the tombs?

Which specifically?
They were both, almost always..

This is just a guess but in later periods Egyptians were burying whole families in one tomb (not sure about earlier history) so perhaps the tomb walls had general family spells and the coffins were used for more individually keyed spells?