hmm, maybe you're talking about a different waterfall model. But as I learned it you spend a lot of time calculating the time and you don't have a lot of flexibility to react because everything has to be done at a certain time and only a specific amount of resources available.
So to this is a classic big business "lets plan our fiscal-year" approach. Maybe you did not really have to use waterfall ? So if you were kinda free-styling you were actually doing agile.
At least that's what I learned in project management you have to specify everything and the other pm has to specify everything. Wasting hours writing about interfaces and problems you cannot know at the time, binding them to a timeline that only works if you tweak and lie about it.
For me "using what I need to get the job done" is the fastest way to do things :) and I pick what I need from scrum, kanban, extreme-programming, pair programming, mob-programming, outlining, UML, ERM, "the hacker way" or whatever paradigms are floating around :)
So at least to me Waterfall done right only works if your guesses are lucky. If you wanna get things done quick and easy the agile manifesto (not to be confused with the different implementations of it) is a better starting point :D
But if you like waterfall, I won't argue against it. I am a pragmatist so whatever works will be used as long as it doesn't slow me down without a worthy trade off -> (for example: branching strategies -> more security, more overhead -> worthy trade off to me)