Similar arguments can be applied to the next aspect I've listed: changes in screen orientation (within the lifetime of the application).
I am making the base assumption that we are talking about screens with an aspect ratio that isn't one (squared screen). This is an easy assumption to make regarding classic devices (desktop and mobile), but less certain if we also consider IoT or wearables devices. Having an aspect ratio of one, however, may greatly simplify the problem (but other peculiar aspects may arise as well).
Even if it's not an absolute truth, you are unlikely to find a desktop device where the orientation of the screen can be easily changed by the user during normal operation. On the other hand, the opposite generally applies to most mobile devices. Therefore, we can safely use the device family again to determine whether our UI will need to adapt to match a change in orientation of the screen.
In practical terms...