I have an installation of zenphoto version 1.4.2.3 that is long overdue for an upgrade. Based on reading the upgrade recommendations, I understand that jumping straight to the current version (1.4.12) might not work. But there are a lot of intermediate builds. Any recommendations for the most efficient path to the latest version?

Thank you!

Well, the most secure upgrade path is step by step. It may work and I did manage to upgrade to 1.4.x from even older version successfully, but those were plain gallery sites without much customizations or complicated themes or plugins.

So even if the upgrade of Zenphoto itself works, you might have work to do on your theme or plugins, especially if you use a custom ones or 3rd party ones that are not actively maintained.

The bigger you jump the versions, the more even small changes naturally add up. Step by step might be easier to catch up with such changes. Which also depends on your general knowledge about these things.

My site is fairly plain vanilla, simply using the default dark theme. I do have some plugins which I'll have to look through. I guess what I'm wondering is do I need to go from 1.4.2.3 to 1.4.2.4, or can I simply jump to 1.4.3 and then to 1.4.4 and 1.4.5, etc?

If your site is a plain vanilla gallery with default theme etc without customisations the chances are quite good for direct updates. I strongely suggest to try with a mirror site first. We only test the update from the prior version.

Yes, that is basically right about the jumps. Also see the info about version numbering here:
http://www.zenphoto.org/news/installation-and-upgrading/#release-number-info