All the time - it’s just the way it is with autos. 8-9 week seed to harvest is frankly the rarity..
I’m an advocate for photoperiods. With an awesome set up like yours.. an 8 week flowerer with 4 weeks of veg time is the same amount of time to harvest as most autos actually end up. Give one a try if you haven’t already and I’d bet ya you won’t look back.
Autoflowers are combing ruderalis, Indica, and sativa (assuming it’s any type of hybrid which 95% if strains now are) .. it’s just more variation and genetic instability than regular photoperiods have and there’s still plenty with those.
Anyways.. when you run a larger grow like this there’s no way to control your timeline or schedule cuz you can’t clone em and therefore you’ll have wild variations between the several plants.
Looking good tho! Keep it up and give photos a run sometime 😉