The conventional wisdom about retirement may be worth re-examining, say two financial-planning mavericks. In their recently published book, “Spend ’til the End: The Revolutionary Guide to Raising Your Living Standard (Today and When You Retire),” Laurence Kotlikoff, a Boston University economics professor, and Scott Burns, a financial columnist whose work appears on MSN Money, use retirement-planning software to systematically test and often debunk the collective wisdom of financial planners.