Exactly! Comprehension is essential to reading! When she next sees pancake in a meaningful sentence she may recognise it, or it may take a few more times.
You are confusing comprehension (understanding what the words mean and, by extension, the ideas the author is trying to convey) with word identification (working out what it 'says')
Your 'guessing from the picture' method may, or may not work. If you presented her with 'pancake' again and no picture she's just as likely to not have a clue what it says as she is to have remembered it (in fact, research* shows that she's more likely to not have a clue). Whereas if she is able to sound it out she'll have no problem at all with it whenever she encounters it again. If it hasn't yet gone into long term memory she'll just be able to sound it out and blend it again. Simple.
or it may take a few more times.
Unless it is in a Look & Say' type story where the word is repeated multiple times in the hope that the child will memorise it, 'pancake' is not a word likely to be encountered sufficient times and sufficiently close together for learning as a 'whole'.
I'm curious, plusonemore. Are you a teacher or an 'expert' as defined earlier?
(*research which I can quote you chunks of if you insist)