There are people I know personally that have gone through every single one of the 1000+ Google interview writeups in glassdoor in order to prepare for interviews. One of my former co-workers showed me 10 pages of questions he distilled from glassdoor of various questions that were reported, and he memorized the answers to all of them, ranging from "find the common descendant of two nodes of a directed graph", to programming an AVL tree on the spot, to pure dynamic programming questions.
If they asked these types of questions 15+ years ago when I started, there's no way I could have gotten into programming. Even now, the caliber of those questions are simply too hard for me unless I sit down days before the interview to get the answer. There's no way I would be able to figure those out within 45 mins let alone 2 hrs, and I'm not dumb. It's ridiculous the level of expectations people have these days.
Sorry, `diverse' is an attribute of the distribution of questions you ask. Not of any single question. If for each interview you take a random question from glassdoor.com (and perhaps even tweak it a bit, if you feel like it), that might even meet the definition of a diverse but not too hard selection. (Unfortunately, I know almost nothing about glassdoor.com, and what kind of questions they have.)