Eh, experiences will vary. For me, my zone is conducting things, not typing. Firing something off in twelve tabs and coming back later is precisely how my brain works.
As someone who gets "in the zone" like the person you're replying to, I just don't get how this could possibly be the same thing. "Coming back later" doesn't make any sense when you're in that state. Stopping and waiting is a killer. You're just constantly doing things without necessarily consciously thinking about it.
Do you mean you're switching continually between the twelve sessions? Or literally "coming back" in a different sort of operating mode?
The closest thing to it for me using AI tools is specifically not running multiple "agents" but making targeted changes over and over and over but with a 10x+ increase in typing-vs-change ratio. (This also rules out things like Opus let alone Fable as they're just too slow and do too much at once.)
I point at the violins. I gesture the drums upwards. Sometimes I make a big broad gesture that encompasses the entire orchestra.
My agents are tasked, in part, with explaining the context with mockups and examples I can poke at for each job.
I don't really get in the zone for raw code typing, that's always been a slog.
I get more distracted if I attempt to focus on just one thing for a day.
Different brains.
Well hang on, why wouldn't you just have another agent planning Y for you? And then just come back and review what it comes up with?