Build an index that counsel can use to search all ESI at once by:
extracting text from native ESI; and
using optical character recognition (OCR) to generate searchable text for ESI that does not contain extractable text (such as TIFF images and unreadable PDFs).
Counsel often use processing tools to isolate ESI that they reasonably expect is irrelevant to the litigation, so that they can exclude it from the universe of ESI that they ultimately move to the document review platform for review.