Perhaps A Rather Dumb Question...

IIRC, there are two main categories: bank-wrapped rolls and customer-wrapped rolls.

Bank-wrapped rolls are basically the "coins mixed up" thing, a big part of which originates from coin counters. Not sure where else they could come from (perhaps from combinations of the occasional loose-coin deposit).
Customer-wrapped rolls are pretty much exactly what they called: rolls that were deposited at bank already wrapped. These often come from old accumulations (not necessarily collections, though that happens too - I'm talking about your typical change jar), which means that they have a somewhat larger frequency of old coins, including silver (and if the change jar was more than 50 years old - which is somewhat uncommon but does happen occasionally - they might well have been fully silver).

Incidentally, I've never heard of anyone getting a full box (or even multiple rolls) of Buffalo nickels, but there's been a CCF member a few months ago who got almost an entire box of wheat cents. Don't recall the thread, unfortunately.

I suppose Federal Reserve is also a possibility, yes (which would explain the occasional box full of one particular recent date).

There are more CRH in your area than you think. I live in a small town and thought the same thing until I talked to my bank manager.

I always assumed brinks collects all coins from a region and boxes them up in that region. You will start to see the same x's and marker marks on coins if you do it enough, which to me means the same coins or at very least the same CRH.

When someone hits a monster box and gets numerous silver I always believed it was someone cashing in an old CWR or someone who got an inheritance that didn't know what it was. The coins stay together, for the most part because they are in the same region or major city.

Again, not sure if this is accurate, but its what I've always bought into.

The brinks/loomis/Garda boxes you see are wrapped by them, at a coin processing facility/vault. Where they collect money and coins from all sources. Your local supermarket, banks and department stores, anywhere they have a contract with. Everything gets logged and dumped into a industrial coin counter, where it is counted and rolled/wrapped. Now you said something about how machine wrap boxes get those dream boxes that we all dream about with 100s of silver and what not in them. Most likely someone turns in grandpas collection into a bank. The bank without any tellers knowing about the true value of the collection, sends it out to their cash carrier, brinks/loomis/Garda. You get the process? When you read about people getting solid customer wrap rolls, directly from the bank. Those rolls just didn't make it into machine wrap rolls yet lol. No one gets coins directly from the fed. The fed does not box their coins, they are bagged up. When a coin processing facility/vault needs coins they go to the fed and picks up those bags then head back to the facility and turn them into boxes.