The great thing about re-reading material or records is that one realizes how easy it is to remember things incorrectly. Are you making a research decision (particularly online late at night, or while researching in those last minutes in a library) based upon what you "think" a record says? Relying on our memory can be a big mistake.
We often realize that great-grandma might not have remembered things correctly when the census taker arrived. Can we expect her great-grandchild to be any better?