I think most clients would be surprised at how often WordPress websites need some piece of code architecture updated. It is RARE that any one site of ours goes a week without an update of some sort, even the smallest ones – usually a WordPress plugin.
WordPress plugin updates tend to come in trend waves. Surrounding an upgrade to WordPress core software, there will be a considerable wave of plugin updates as software needs to be changed to represent the new version of WordPress.
Some plugins have their own gravity for creating updates. For example, an update to The Events Calendar might generate several other updates of related plugins. Instead of one plugin to update, you might have four.
Some plugin updates create their own ripple. The WordPress community has feedback mechanisms for plugin code providers, so developers can let them know issues that occur with updates. Sometimes a plugin update runs into conflicts with another plugin, or a theme, or even server specific software. This can cause multiple updates of the same plugin over days as the developer solves these issues.
This is why we almost always wait on updating plugins and themes for a few days UNLESS they are a known security issue. Waiting a few days for the newest version of a plugin usually doesn’t have much of a downside, but creating a conflict on the site between plugins can. That’s why we also do not choose to use automated updating of plugins – the value is so little to automatically updating plugins, and it actually can get the developer out of touch with what is on the site. It may take a bit more time to review plugins after a few days before updating them, but it saves work in the long run.