[mmorett]

Let me offer an explanation: maybe the job he was applying for asked for knowledge and experience in Java, Spring, Hibernate, Grails, Javascript, SQL, CSS, writing stored procs with PL/SQL, performance tuning, node.js, and Git...and the binary trees/linked lists portion only pertains to Java (and maybe Javascript?). More specifically, maybe the guy just hasn't had the need, for whatever reason, to use a binary tree or a linked list recently. I doubt he runs around saying "it's April, I haven't used a TreeMap in a while, let me use one now so it's fresh in my mind for next year's interview".

The point I'm trying to make is that some requirements are very, very wide/broad. And then they'll take one piece of that broad pie and decide to go very, very deep.

And then there's the death knell...you spent time developing deep expertise in something no longer actively used. This applies more to frameworks than languages (i.e. Struts, Prototype, Dojo, etc.)

It's a no-win situation all around.