"From time to time, you may need the convenience of overdraft protection. Think of it as peace of mind for those times you need a little extra to cover a cheque or bill payment." This is from the BMO website.
During university I worked at one of the big 5 banks as a teller and I helped out with the processing of loan applications. I learned about the joys of determining your Beacon and FICO scores. Two of the main personal finance habits were learned while making $8.00/hr counting other people's money.
1.) Bank Overdraft -- Yes, they will protect you for those times when you may have forgotten to deposit your rent cheque or your cousin is two days late paying back your $50 loan. However, nothing is for free and the bank charges you interest on the overdraft amount each day. 9/10 you end up using the overdraft protection because you were either too lazy to get to the bank or you failed at planning your personal finances and you bought that new watch or the case of Guiness instead of Lakeport beer!
2.) Instabank fees -- Yes, most banks will charge you hefty service fees for using your own money. One big tip is to get out of the habit of withdrawing small amounts from the bank machine at one time. Each time that you make a withdrawl your account can get charged and if you are using another bank's machine then you're getting the 'ol double whammy of even more fees. Instead of taking out $10 each day throughout the week to buy your foot long sub combo at Subway, then why don't you take out $50 on Monday and budget it throughout the week.
It's the little things that make the world of personal finance in Canada go round.