I have numerous online banking and credit union accounts. Generally speaking, I have them send me paper statements if I don't have to pay for the service. I do this because I know it will compel me to look at the account at least once a month. I don't always bother to download my E-Statements.
This month I was looking at a statement for one of my bank accounts and I noticed a $500 withdrawal which I didn't authorize. I called the bank and was told a teller mistakenly pulled the money from my account because of inadvertently switching two digits from someone else's account number. They immediately replenished the account and the $5 service fee I was charged because I was below the minimum.
In all my years, I can't recall this ever happening to me. This experience has reinforced the importance of examining all my accounts at least once a month. Admittedly, I didn't always do this in the past.