PDF bookmark hierarchy depth is always the same as the ToC hierarchy level, even if ToC is not used.
If ToC hierachy level is undefined (not set), then it should default to 6.
Check with a page that was already exported
No custom value (should be 1)
Has a custom value that was manually set
Has a custom value from the profile
Check with a page that was never exported (should be 6)
Export without profile
Has a custom value that is manually set
Has a custom value from a profile