Claiming early may still be the right move for some people, such as those with serious medical issues or a family history that suggests they're not likely to live to a ripe old age. But with people living longer and retirement sometimes lasting decades, it's best to make deliberate calculations and see if you can wait longer in order to collect more.MYTH NO. 5: You should rely heavily on bonds rather than stocks as you get older. That common advice made sense when retirements were shorter and inflation didn't have as much time to erode savings. Planning for a 30-year retirement, as you should do now, changes the thinking. So does the fact that the outlook for Treasury bonds isn't as bright, with the government loaded with debt and future inflation fears high. To figure out what percentage of your investments should be kept in stocks, advisers now recommend keeping 110 or 120 minus your age in stocks, updating the old guideline of 100 minus your age. And consider high-dividend stocks that can replace some of the income that is often sought from bonds. MYTH NO. 6: Any retirement target-date fund will allow you to "set it and forget it." It's true that target-date funds are an appealing option for 401(k) and other retirement plans. The funds automatically adjust to a more conservative asset mix approaching retirement and the fund's target date. But they can give consumers a false sense of security and lull too many into ignoring their savings, at their peril. They also vary widely. A review by the Securities and Exchange Commission showed target-date funds from the same year had as little as 25 percent or as much as 65 percent exposure to stocks. If you invest in one, understand the "glide path" (how the allocation changes over time), how much and when it turns the most conservative, and whether you're paying more in fees than with similar target funds.