This is just a guess, but when your website is eventually checked by search engines every day, it will probably be done at roughly the same time every day. In any case, it is better to assume that it is, rather than it is not, done at the same time every day.

Let's assume for the moment that search engines do, in fact, check your website at the same time of the day.

If it is true, your postings to the website are best spaced 24 hours apart so that every day, a change is noted. If search engines scan your site at an effectively random time of the day, then it won't hurt to make your blog posting at the same time every day, will it!

If Tuesday's posting were published at 6pm (on Tuesday) and Wednesday's posting was published at 4am (Wednesday), and if a search engine indexes your website at noon every day, both postings would present as a single change at noon on Wednesday, and no change would present on the day before, Tuesday because Tuesday's posting was published too late in the day to get picked up by the noon scan by the search engine.

It's like taking out the trash. If trash collection occurs every Friday morning, putting it out at the same time every week is the way to maximize your use of the service.