Ranking a rootdomain - observations:
When your domains is a 100% EMD, then you can go totally wild with the keyword that matches your domain. Simply cause it's not a keyword anymore but it became your BRAND. And Google does NOT punish sites for branded keywords.
When your domain is not an EMD, or only partial then you have to be careful, and use something like 40% brand 40% url and 20% divided over all keywords that you want to rank for. (don't hook me up on these percentages, can also be 60/30/10 or 50/25/25 or whatever).
Ranking an innerpage - observations:
Somehow the filters to rank innerpages are a lot less tight. I've ranked tons of innerpages by only using 1 anchor txt, never had any problems. Still I would use a few variations just in case, like 3-4 keywords instead of one.
Maybe someone else mentioned the above already, maybe not, anyway there is a lot being said so I rather judge it myself and the above is what I observed.
Keep in mind it's not only about anchor diversity, it's also about a correct ratio of low vs high PR links, if you have 1000 blogcomments and only used your url as anchor or 1000 different keywords then there is a huge chance that you will get hit by the update.
So in short again:
When you want to rank innerpages then don't waste your links on click here and other nonsense but use the keyword and very relevant combinations. Lately I ranked a client for a keyword, we targetted the homepage and the innerpage with that keyword with an exact equal amount of links, before I started the homepage and innerpage ranked at #12 and #13. When I was done the homepage didn't rank for "that" keyword anymore (luckily still for plenty of others) and the innerpage ranks at #5 now.
Then I work for some lead generators where we target dozens if not hundreds of url's at the same time and it all ranks great with only 2-3 variation of the keywords.
Then I worked on some other client sites where we targetted only the homepage with a keyword that didn't match the domain (at all) and a few sites dropped hard (luckily not all).
Sometimes homepages still rank very well with only 1 anchor and well, I guess that is a bug in Google's system, some things are just not explainable but in most cases those rules apply.