I quite agree with your observations. What puzzled me was whether the percentage withdrawals excluded conversions to a RRIF. Of course, many people draw on their RRSPs or RRIFs before the compulsory age 71. As others mention too, it is a wise strategy to start to draw down these accounts "early" choosing to pay a modest tax and reduce the chance of hitting the OAS clawback..
My wife and I split our pensions (RRIFs) and pay an average tax of around 12% of our gross income.