how important is visual imagery in hypnosis

i was thinking that visual imagery is very powerful in effecting the body. we do it everyday almost all the time. when we worry we visualize bad possibilities in our head and then we experience the feelings of what that experience would feel like in our bodies as if it was happening to us and when we are excited about something we visualize in our head the really good experience that might happen and we feel all the good feelings as if it was happening to us now although it may never even happen. experts say that this is because the nervous system and brain can't tell the difference between something that is real in our environment and something we visualize in our head.

it seems that hypnotists understand this and use it on there subjects. imagine a ice block on your head for long enough and you may begin to experience numbness or imagine your arm in concrete and you may begin to experience your arm feeling stiff and etc..

im guessing that visual imagery is very useful in many things including hypnosis to make things easier for the subject and hypntist. but do you really need to use visual imagery in hypnosis?

i have seen many times a hypnotist put there subject in trance and then without any imagery just say" when you open your eyes you won't see me etc.." or "go deeper" with out imagining any steps to go down or "your leg is getting very numb now etc.." or "you are begging to feel drunk"?

so is hypnosis more about just talking the subject into experiencing things and is imagery just maybe a extra tool that doesn't always need to be used or doesn't need to be used at all?

but stage hypnotist othen look for good visualizers to make there job easier so maybe visual imagery is a big part of hypnosis?

is visual imagery that important or can you just use simple worded seggestions to get your effect would it take longer this way?

hope i made sense any useful replies would be helpful