Intake manifold and other parts around it can be removed without removing of head if that is the main goal. If you want to see the situation inside engine and make a refresh that is another story, but not something additional to some main external engine work in my opinion. If you remove it will not be strange to not like what you see and to not want to close it like this without some more special check and work from head specialist at least that is the normal way in my opinion.