NEW YORK ( MainStreet) — It's one thing many of us used to do, probably weekly, but we don't do it at all anymore: Set foot inside a bank branch. That's the surprise finding in a new survey conducted for that reported that three in ten of us had not been inside a branch in six months.

Expect that number to vault over 50% within five years, said Greg McBride, Bankrate's chief financial analyst.

The real surprise in the Bankrate numbers: old, young, in between, we all are avoiding branches. Many experts had thought Millennials were boycotting them but, in the Bankrate survey, 20% of retirees have not been inside a branch in a year.

The reason: it just is more convenient to bank without branches, 24/7, when and as we want.

Increasing numbers of new-style banks now offer branchless service. Included are Ally, Movenbank, Simple and GoBank.

Fact: I have personally been inside branches three times in 15 years, each time involving real estate transactions. The last time I was in a branch - a Chase in Las Vegas, to arrange a wire transfer - I was the only customer.

There is one thing - and really only one - that may cause you friction in a branchless lifestyle. Think on it. You'll find out at the end of this story.

But, first, the big question is: why do banks keep branches open? You'd have to ask them.

"Bankers know there are many thousands of branches that should be closed," said Jim Matous, a bank marketing expert based in Cleveland. They are hesitant to pull that trigger- fearing political and customer fallout - but, eventually, that day will come, said Marous, because we as a people are abandoning branches.

"The only time most people go into a branch is because something has failed," said Tom Dougherty, CEO of Stealing Share, a branding firm in Greensboro, N.C. that has often worked with financial services clients. The mistake many bankers make, said Dougherty, is believing their branches are integral to their branding, "All they are today is very expensive billboards," said Dougherty.

Dougherty's right: a lot of the customers in branches are there because they are mad. A check bounced, a deposit was declined, they were rejected for a loan. And they want to vent.

That is understandable. But do you want to stand in line behind them?

One of the last times I was in a branch I stood in line 15 minutes as the fellow in front of me refused to understand why the teller would not accept a third party check for deposit to his account. This was a check made out to XYZ, who endorsed it over to ABC, and now PQR wants it as cash.