There were slender insights derived from three days of amiable and uneventful questioning of the four CEOs of major banks at a parliamentary committee in Canberra this week.More an indulgence than an inquiry, the industry's critics and champions of a royal commission will scarcely be satiated on what they've learned.But it'd be a mistake to regard the exercise as a waste of time.At the bidding of a nervy government, the custodians of the Australian banking oligopoly made the most of their time before an internet and pay TV audience of opinion formers, among them institutional investors (the only stakeholder of interest to any big business CEO).The MP's questions catered to a range of special interests, the needs of banking sector news bulletins (perhaps unintentionally) among them.Given this newsletter's target market and the biases of its editors, hours on matters related to credit cards suited us.The mainstream media may be less forgiving, the panel of MPs armed with little or nothing new on old scandals (such as financial planning, CommInsure, Timbercorp).Then there were Banking Day's three priorities for any banking inquiry. How'd we fare? As expected, not too well but nor do we leave disappointed.One was: the post 1980s financial deregulation industry structure, featuring a wave of demutualisations, a topic David Murray's panel for the Financial System Inquiry found of little interest. That one waits for another day.A second: insight of the modern history of the industry.Ian Narev from CBA delivered a nugget on the position of Aussie Home Loans when the bank put its foot on a once loathed challenger in 2008. We're following up.And then there was the industry cost structure.Labor MP Pat Conroy pursued the topic, most engagingly with ANZ CEO Shayne Elliott on WednesdayThen at a much more micro level Westpac CEO Brian Hartzer uncovered a glimmer of treasure on unit costs, albeit in ATMs.