The answer varies according to the environment:
Technically, it take takes 4-6 hours if it's done in one session and all the pre-requisites and requirements are already in place.
However, that is rarely the case and a lot of the time unexpected delays can occur (ports not open, pre-requisites not installed, can't get an a SA account, etc.).
Therefore, a more accurate estimation would be 2-3 session each of 2-4 hours.
When working with SkypeShield SphereShield credentials an internal Bastion is required and therefore the installation duration can get longer, it can require up to 2 more hours and will likely require another session.
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Note that very large environments with multiple pools, Front Ends, Edge server or a requirement for HA can prolong the installation time.
Below is a summery summary of hours for basic installation:
Topic
Time frame estimation (hours)
Preparing system requirements
8
Initial installation and requirements verification
2-4 (Depends on topology)
Configuration finalization and additional installation (if required)
4
Training and enrollment
2
Further testing
2
For dedicated credentials, add one more session of 2-4 hours.