Updating core from 8.5.4 to 8.6.3, can I skip the releases in between? I have a website that is running on Drupal 8.5.4. I want to update it to Drupal 8.6.3 through the manual update option (link). 

Can I directly update it to 8.6.3 skipping the releases in between? None of the releases in between (8.5.5, 8.5.6, 8.6.0, 8.5.7, 8.6.1, 8.5.8, 8.6.2) had updates to the default.settings.php file, and I don't have any custom modifications to the files composer.json, .htaccess and robots.txt either (which means I can overwrite these 3 files with the ones that come with the updated Drupal code).

I read somewhere on the internet (link) that, while updating Drupal, we can skip minor and patch updates in between. But the release notes for 8.6.2 (link) says sites running Drupal 8.5.X should first update to 8.5.8 and update to 8.6.X later.

Does this mean I should first update to 8.5.8 and then to 8.6.3? Or can I directly update to 8.6.3?
You can skip releases and update directly to the latest release, unless you want to narrow down update issues by taking smaller steps.

You've mentioned the release note for 8.6.2: 


  Sites on 8.5.x should update immediately to Drupal 8.5.8 instead, and
  plan to update to the latest 8.6.x release before May 2019.


This had a different background. This advice was for an urgent security update of versions &lt; 8.5.8, because this wouldn't have been the right time to evaluate the update to 8.6.x if you hadn't done it yet, while the minor update from 8.5.7 to 8.5.8 was easy to apply, because it didn't require a database update.