This would be done in parallel for key sources.
There is a lot of information on physical devices that is helpful, though. Even discovering additional apps and services used on the devices can lead to more discovery via those cloud services, if relevant.
Physical devices have a lot of additional information, though: Files people are actively working on, saved snippets and screenshots of important conversations, and synced data that might be easier to get offline than through legal means against the providers.
In outright criminal cases it's not uncommon for individuals to keep extra information on their laptop, phone, or a USB drive hidden in their office as an insurance policy.
This is yet another good reason to keep your work and personal devices separate, as hard as that can be at times. If there's a lawsuit you don't want your personal laptop and phone to disappear for a while.
In these situations, refusing to provide those keys or passwords is an offense.
The employees who just want to do their job and collect a paycheck aren’t going to prison to protect their employer by refusing to give the password to their laptop.
The teams that do this know how to isolate devices to avoid remote kill switches. If someone did throw a remote kill switch, that’s destruction of evidence and a serious crime by itself. Again, the IT guy isn’t going to risk prison to wipe company secrets.