I’ve been using IS doc type and publishable doc type intensively. My usual practice was to create a dedicated publishable doc type for publishing purpose and IS doc type for processing purpose even though their contents are the same.

Is this action redundant? Can I use publishable doc type as IS doc type even though I won’t publish them? When its used as doc type function, will the IS trigger services subscribed to the publishable doc type ?

yes, it doenst make sense to create 2 documents only to differentiate between publishable n not-publishable.