I would keep all my w2’s. What would happen if the IRS electronic records were compromised and they were somehow changed or lost? You can never be to paranoid when it comes to ensuring you get what you worked for all these years

we scanned in a bunch of old stuff, have originals of birth/marriage/house deeds, various titles in a safe deposit box with our kids names on it. We put statements from all our accounts in about every six months along with updated contact info for our kids. Also we have cd’s with all our family pictures on it. Now days I don’t think photos are nearly as important. We have tons on everyone’s electronic devices.

I would evaluate each category separately. Obviously when we moved six years ago we had owners manuals and sales receipts from items we no longer had or were ancient and we would have replaced if they broke. Not as bad as my MIL who had a big pile of boxes and the original packaging from old items. Just in case. Most manuals are online now anyway. They were all trashed. Documents like house buying/selling, not a bad idea to keep.

We keep no medical documents at home.