Development, like construction, is horribly ineffective at accurate projections. So if it's "your turn" to have the (singular) long lived feature branch, you will run over your deadline and into someone else's start date. There will be someone you're blocking who starts pressuring you to finish or for the org to make an exception and allow 2 feature branches.

And six months later, what was good for the goose will be good for the gander and then you have 2 feature branches part of the official process. Which of course means you'll occasionally have 3. After that it's like Texas Highways. They just keep getting more lanes and traffic gets worse.