Many of my clients download their bank transactions directly from their banks online system. Some, however, only do this once a month when they are ready to reconcile all of their accounts. There is one very strong reason I recommend completing the bank download feature in Quickbooks at least once a week.
I have experienced this personally, and I have seen it happen to my clients.
You could be in for a very rude awaking as you trod along during the month keeping track of your account register as you enter each transaction that you complete. Then one day you get a phone call from the bank saying you are overdrawn. Or, perhaps you are out in the field and attempt to use your credit or debit card only to have the charge declined.
Downloading regularly can bring fraudulent charges to your attention immediately and allow you to dispute those charges before overdraft and/or over limit charges start to pile up on your account. It's much easier to get credit for these charges with your bank as soon as the fraud is detected then it might be a few weeks or even months later.
You may think that you have nothing to worry about. You take every possible precaution you can think of to prevent identity theft. You shred every paper, pay monthly fees to a credit monitoring service, and more. But a stolen debit card number can wipe out your cash on hand in one day!
Consider keeping your personal records on Quickbooks (in a separate "company file") so that you can use the bank download feature for these accounts as well. Being diligent, and monitoring for yourself is your best defense.