At the risk of sounding totally stupid, what do y'all store in there? I am not in a stage of life where I get a ton of paper in the mail that I need to file or digitize. I pay basically every bill online with the exception of my car payment.
However, I have been thinking lately that I need to get better about saving information that I get online. For instance, bank statements. I know some people download them, review, and file them away. I haven't really kept up with them like that. I also have various things in my email.
I already have a terrible tendency to keep things. I know on my external hard drive that I have things that I wrote for school (think middle school) like ten years ago.
TL;DR: What do you keep? What goes in there?
Udontno,
Good questions, I'll give it a go. If you're only 10 years out of middle school, then I'm a lot older than you

First, I'm almost completely paperless, making a major effort over a couple of years to get rid of boxes and boxes of old papers.
Banking and credit card statements: Downloaded from the bank each month, named with bank name and date for easy retrieval. It's invaluable to go back to old statements, even years later, to look up proof of payment or get information. I have successfully made warranty extension claims on purchases made with certain credit cards 2 years after purchase. Records needed, of course.
Bills/invoices: Utilities, HOA statements, contractors, insurance
Medical: need these for medical records and for tax deductions
Home records: keep track of improvements for tax purposes when you sell your home. If tax laws change (they have many times in the past) or if you ever rent out your home, you will need to calculate your cost basis and previous depreciation and other costs.
Tax records: self-evident. Keep backup for deductions for 3 years or so, and your tax returns forever.
Investments: Keep cost basis information until you sell the investment and record on tax return; then 3 years afterward. If you buy mutual funds or DRIP plan stocks periodically, you need to keep investment statements indefinitely for cost basis calculations.
Receipts: Keep 3 years' worth or so for proof of purchase, warranty claims, etc. Returns to Costco (and other retailers with good return policies) are easier with receipts. Scanned receipts are fine; it's impossible to keep track of those flimsy "paper" receipts.
ID cards: Social Security, Health Insurance/Medicare cards, Rewards/Loyalty cards, Passports, Military/Veteran's ID, voter registration, TSA Known Traveller number. I keep all of these in Dropbox so they are available on mobile devices.
Car registration, proof of car insurance, Driver's license - save in Dropbox, available on mobile device.
Instruction manuals, model numbers and serial numbers for appliances, electronic devices, etc.
Records of security freezes on credit bureau accounts. I have a security freeze with Equifax/TransUnion/Experian. Keep records of these and the PINs required to un-freeze with needed.
Pictures and paper records for home inventory - in case of fire, theft, etc.
Travel documents: tickets, reservations, contact information. Keep in Dropbox for access from mobile devices when traveling.
Birth Certificates, Marriage licenses, etc.
All of this information is easily backed up to local inexpensive disk drives and cloud backup (in my case, BackBlaze).
Trust me, as you get older your record keeping requirements increase. In recent years I have taken over finances for an elderly parent. Most of the above records are needed for her also.
Make sure to keep things simple. Don't use proprietary data formats - plain PDF files are great; they will probably never be obsolete. OCR'd documents help for search lookup. Remember that storage media become obsolete also. Don't use CDs or tape. Remember floppy disks? Good luck trying to read data from them these days. For now USB-connected external disk drives and cloud backup are good. When these media and services change, you can copy data to future media and services.
Let us know if this helps. I wish I had been able to start the digital record keeping started early in my life. Couldn't do without it now.