Major update, awesome. /s
As someone who manages a network of 250+ WordPress websites - these PHP updates are killing me! As soon as I'm done helping clients upgrade/fix their incompatible themes/plugins and custom code, a new version is out! Even with great tools, the process for about 10% of my network is a nightmare.
While I appreciate the work, it's not very satisfying and for many clients very frustrating to pay for something they know nothing about, just to "keep the lights on".
The plugin/theme developers usually develop with older versions of PHP in mind, lot's of plugins still work even with 5.x versions...
For my WP sites I just stick with "two major versions behind" workflow and I don't encounter many problems.
Am I doing it wrong?
Eventually you have to upgrade. Do you want to go from 5.6 to 8.2 and possibly have to start over? Or do you want to go version by version, paying smaller amounts more frequently to stay current?
Also: WordPress + Themes + Plugins works best when you don't delay maintenance/upgrades. Everything needs to work in concert. You might be able to freeze your theme in time, but your plugins and the WP core will march on.