Anyone using a card for less than $20 is a fool. I'm not going to spend an extra nickel on gas either, cash wins.
Name one reason why.
Overusing the card turns the statement in an incomprehensible mess, so if there's a transaction that wasn't made by me buried in there, it'll be much more difficult to notice. So I always keep a fair amount with me to use on the small stuff and refill that every month.
Sorry but the accountant in me found that hilarious to think that your personal bank statement could be an incomprehensible mess. Your personal bank statement is minuscule compared to the statements of most companies, and I deal with those statements every single day.
Another thing is that if your statement is that large, then maybe you should be checking it more than once per month. I personally check my own bank account once per week. I check it every weekend. It's pretty easy to look through one week of transactions for anything fishy.
Hell, it is the Internet and smartphone age, I check mine daily. Just sit down with my phone at the end of the day and make sure that all of the charges/pending charges for the day make sense. Takes me maybe 2-3 minutes total. ---
I am a senior software engineer. If you see me post here, I am tired of writing TPS reports.