Agree the staggered introductions have been in the works for some years. I remember PARURES DE SAMURAIS - 2017 - the marquee design of that season that came out wayyyyyyyyyyyyyy later than the rest - 6 mos or so
Along with the staggered intros are the staggered outros. About 2010ish, scarves were in the stores/internet for NO MORE than 2 years, then they were whisked off the sales. Then the design was on hiatus for a while, arguably a limited production run.
But, if you look at the internet now, you will see some merch that far exceeds the 2 year limit, production no longer stops at 2 years.
Arguably, the later availability of variants eg wash is just another way to keep the design in production longer while maintaining the illusion of limited production runs