I think the time to upgrade is largely determined by the time to shutdown and restart all the tasks. The actual upgrade, when we'll practiced with all pieces (upgraded drivers?) in place just takes a few minutes no?
As always... try in DEV or QA and create a mini personalized playbook such that no step is forgotten in PROD and the approximate duration of each step is known.
Hello @MoeE, piggy backing on what @Heinvandenheuvel is saying (Hein long time! I hope all is well with you, we miss you). Testing is where the bulk of the time should be spent. Full business and performance testing should be done in non-prod to ensure that when you upgrade in production there are no surprises. This will also give you a good idea on how much downtime will be needed. There is a community article that branches into other articles which would be good to review.
If you want help with planning and testing the upgrade you can reach out to your account manager to have an engagement with the Qlik Services team.
