As you scan, and before you shred, you might want to verify that you have definitely scanned the initial evaluation.
Maybe there is another really important part of the scanned chart, but that is the only one that I would really miss. Insurers can want a copy of the initial evaluation from 5 years ago to justify authorizing a new treatment. It's usually not a problem if an old progress note is missing.
Remember, the reason we "want" to have a copy of old records is to help defend our self in court.