Re: What is the Problem?
Ok, I'll bite:
I guess 30-40 years ago every month you started off from the previous month's statement and tallied up cheque stubs and card receipts that you had been accumulating and you made payments for utilities using cheque, bank transfer, or going round to their showroom or office or whatever and paying instead of setting up direct debits. If there were no discrepancies you filed away the current month's statement and destroyed the bits of paper you didn't need otherwise you complained to the bank.
Now cheques are practically extinct as are branches, showrooms, and offices, most utilities are paid by direct debit but you may not know the amount till after it's taken out, online card payments don't generate receipts unless you print them out yourself, continuous payment authorities are a thing, debit and credit card holds are a thing too but you might not know exactly how much is being held till you log in, you may have other financial products with their own balance and statements which charge to your bank account (e.g. PayPal), and your bank statement is more of a floating window over a list of transactions, certainly during the past few weeks.
If you were to wait a month before checking your account and there's fraud on your debit card your current account might get emptied out. Also, if you were to report fraud a month later you might not even be taken seriously.
So those are reasons to log in every few days and keep an eye on your account.