The challenge in Splinter Cell games has always been about completing your objectives unseen. In Splinter Cell Conviction, Sam Fisher, now free from the Agency, basically abandons the whole idea of sneaking. Why hide when you can just shoot dudes? Sure, if there's a handy column or whatever to hide behind, okay, but it's not like Fisher seems overly concerned with being invisible.
Unless he's hiding at full speed down that hallway, or in that plate glass window.