Understanding how your audience uses technology to interact with your digital presence is a vital part to reaching them successfully. This is why I advocate a detailed analysis of your audience's online life—technographics, to borrow a term from Forrester Research—in your planning.
But, you don't need to do (or pay for) that research yourself. You can use the research of others to apply to your circumstance.
This article from A List Apart goes into detailed analysis of research into device usage. Take a look, and see. And whether you're a one-hander, a cradler, or a prayer when you hold your smartphone, you'll see where you fit in with the general population. And, more importantly, you'll garner new insights into your audiences when you're creating interactions for them.