Is it important to restart the computer after installing a software or update?
Is there any reason why it needs this reboot or why its not always one way or the other?
The answer is that it depends.
If the software being installed affects an integral part of the operating system then a restart is required.
For instance, a new kernel for the operating system.
Therefore, the DLL will be locked on disk.
Hence, there is a need for a restart.
Generally, restarts between install and running are because you are replacing system DLLs that are locked.
Restarting allows the changes to be made in a safe way without interfering with active tasks.
It also allows system security that processes monitor changes to system files to ensure that unauthorised changes arent made.
Similarly, in the case of Apples MacOS, a restart is required only after a system update.
Despite improvements in technology, theres no apparent end in sight for the restart cycle.
source: www.techworm.net