I've seen Dual Track used several times during upgrading. It's usually a significant Upgrade jump and usually over a significant period of time for emergency fixes to keep business as usual. So I'd not expect significant projects to be running parallel.
My current organization hasn't invested in CHarM, Solution Manager, Testing Tools and is mainly on premise today with an ambition to move to the cloud. And I've seen posts on "How" to Dual Track but not picked up on "Why" Dual Track for releases. So for example when we moved to S4 1709 we Dual Tracked, but what about subsequent S4 upgrades what factors should be considered.
Just wondered if you could share as I am curious.
For more information on our organization, these are some blogs and posts to help frame my ask as it explains our landscape :)