Any Ghostbuster (individual or agency) who's worth their weight in gold knows that zapping, and trapping the reported paranormal pests is only HALF of the battle. The other half is actually spending some time doing research and development.
The concept even goes so far back as when Ghostbusters INC. was first founded, Doctors Stantz and Spengler were constantly doing research and development, with many of their advancements augmented by many paranormal publishing such as Tobin's Spirit Guide, Spate's Catalogue of Nameless Horrors and What to Do About Them, and several others. The 2 aforementioned Doctors even went so far as to compile the most iconic and prolific cases they've seen and put them into a comprehensive and accessible guide.
As Ghostbusters, we're predominantly "Science Guys", "Academics" and "Researchers", and we have to undergo A LOT of trial and error to figure out the problems/issues, just as we do in life. More often than not, we don't always get the bust on the first try because sometimes, we don't have the prior knowledge or prep time before we respond.
But, just as Mr. Zeddemore has shown them (and by extention, taught us), the knowledge doesn't have much use without practical applications. It takes an even amount of brains, brawn, bravery, and bad-assery to be able to be a ghostbuster, AND even then, they only get you so far.
Whether it's researching, putting together, and testing some new and experimental equipment to add to our ever-growing and evolving arsenal of anti-ectoplasmic armaments, or reading into the history of the paranormal problem that requires our assistance, and sometimes both.....All efforts mean to help us develop strategies and inventions to help solve the case.
There isn't exactly a textbook to study for Paranormal Activity, so when it comes to referencing and researching the problems as they come across our doorsteps, we have to go with the next best thing.....whatever we can find. Now while there are a good number of Publications that will see a frequent changing of hands in Occult Bookstores and Libraries, there aren't always enough copies in circulation to go around, especially between agencies and other franchises. And as time goes on, sometimes new entities with little to no prior documented details will manifest.
Just like people, not all entities are the same, and other than the Classification System, there's no real template to study and memorize, or make into flash cards...Different entities have different powers, abilities, motivations, and intentions.....and sometimes they come into play as we travel. Sometimes, you'll come across a ghost who wants nothing more than to eat like it's an "All-You-Can-Eat Buffet"... Sometimes you'll come across an entity who worked his life in such an imprinted routine that it carried over into their afterlife such as a Chef, or a Taxi Driver. Sometimes, they want to correct a mistake they made in life, sometimes, they want to protect a loved one.
And in some cases, as Tobin found out, some of those entities are geographically exclusive to specific places, people, and items.....usually relics or people with connections to a time period long since passed. Some like to remember the old ways of the days, some want to bless people who pay reverence and appreciation to them, and some (like Vigo the Carpathian) want to bring back the old ways with a lethal adamance.