Rarely. I find that most of my data structures usually fit in the category of Lists and Dictionaries. At worst, there are some trees, or maybe a linked list, though usually not implemented in that exact way (mostly just for data to be bound to a treeview-type control. I usually have no need for a matrix.
I know, it seems absolutely incomprehensible. But read the link in the original post. There are programmers who can barely write Hello World applications applying for jobs, and in mass numbers. I know from experience that some of these people actually get jobs!