PDF material comes with different information density. If you have a lose collection of 100 manuals, and you need to find a snippet of information that could be in 10 different ones, I'm guessing something like this can help you navigate and locate what you need.
That would be a great litmus test for these programs. Dump gigabytes of manuals and ask "how many pins does the 74LS04 have?" "What size bolts hold the oil pan on a 73 Porsche?"
PDF material comes with different information density. If you have a lose collection of 100 manuals, and you need to find a snippet of information that could be in 10 different ones, I'm guessing something like this can help you navigate and locate what you need.