3. Apply retention rules instead of judging each document
Now go pile by pile and apply a rule. Rules remove the anxiety, because the decision is made once for a category rather than four hundred times for individual sheets.
Keep permanently, in a separate safe place: birth, marriage and death certificates, passports, citizenship and immigration papers, wills and powers of attorney, house deeds and the mortgage completion file, pension and life insurance policies, share certificates, and qualification certificates. These are the documents whose replacement is slow, expensive or impossible.
Keep for around seven years: anything supporting a tax return. In the US the IRS generally recommends three years and longer in specific cases; in the UK, HMRC asks self-employed people to keep records for at least five years after the filing deadline, and landlords longer; the Canada Revenue Agency asks for six. Keeping seven years of tax-relevant paper covers all three comfortably and stops you researching each time.
Keep while relevant: current insurance policies and the previous year, warranties and receipts for the warranty period, vehicle registration and service history while you own the car, tenancy agreements and deposit paperwork until well after you move out, and utility bills for a year.
Keep one year and then bin: bank and card statements once you are sure they are available online, payslips once the annual summary arrives, and general correspondence.
Everything else goes. Instruction manuals are almost all available as a PDF from the manufacturer, so recycle the paper and keep only those for appliances with warranties still running.