After certain point it's come down to basic things like reading speed/speed at which you can understand an argument. Unfortunately there is no easy way around this. I am not sure even a tutor can help someone go from 740 to 780. Maybe guys like Ron/Stacey can but my best guess is that majority of tutors would fail to help someone achieve that level. If you read some LSAT forum where people go from 90%ile to 99.9% ile you would find that people spend an insane amount of time doing threadbare analysis of past LSAT questions. Google "Blind Review" LSAT to get an idea.
It's easy to say you can't do it , you are not good enough. It's much harder to step in your shoes and achieve the improbable.