Back in 2005 when I wrote DWiki, the engine that is used for Wandering Thoughts, there was an accepted standard structure for blogs that people followed, me included. For instance, it was accepted convention that the front page of your blog showed a number of the most recent articles, and you could page backward to older ones. Part of this structure was the idea that you would have a page for each day and that page would show the article or articles written that day (if any). When I put together DWiki's URL structure for blog-like areas, I followed this, and to this day Wandering Thoughts has these per-day pages.
I now think that these per day pages are not the right thing to do on the modern web (for most blogs), for three reasons. The first reason is that they don't particularly help real blog usability, especially getting people to explore your blog after they land on a page. Most people make at most one post a day, so exploring day by day doesn't really get you anything more than links in a blog entry to the next entry and the previous entry will (and if the links have the destination's title, they will probably be giving you more information than a day).
The second reason is that because they duplicate content from your actual articles, they confuse search engine based navigation. Perhaps the search engine will know that the actual entry is the canonical version and present that in preference to the per-day page where the entry is also present, but perhaps not. And if you do have two entries in one day, putting both of their texts on one page risks disappointment in someone who is searching for a combination of terms where one term is only in one entry and the other term is in a second.
The third and weakest reason is a consequence of how on the modern web, everything gets visited. Per-day pages are additional pages in your blog and web crawlers will visit them, driving up your blog's resource consumption in the process. These days my feelings are that you generally want to minimize the number of pages in your blog, not maximize them, something I've written about more in The drawback of having a dynamic site with lots of URLs on today's web. But this is not a very strong reason, if you have a reasonably efficient blog and you serve per-day pages that don't have the full article text.
I can't drop per-day pages here on Wandering Thoughts, because I know that people have links to them and I want those links to keep working as much as possible. The simple thing to do is to stop putting full entries on per-day pages, and instead just put in their title and a link to them (just as I already do on per-month and per-year pages); this at least gets rid of the duplication of entry text and makes it far more likely that search engine based navigation will deliver people to the actual entry. The more elaborate thing would be to automatically serve a HTTP redirect to the entry for any per-day page that had only a single entry.
(For relatively obvious reasons you'd want to make this a temporary redirect.)
There's a bit of me that's sad about this shift in blog design and web usage; the per-day, per-month, and per-year organization had a pleasant regularity and intuitive appeal. But I think its time has passed. More and more, we're all tending toward the kind of minimal URL structure typical of static sites, even when we have dynamic sites and so could have all the different URL structures and ways of accessing our pages that we could ask for.