The puppet show (which is incredible) builds up how Luke’s sacrifice has inspired the galaxy, but the dialogue I’m talking about suggests that the galaxy hasn’t been inspired and remains as hopeless as ever.
Beyond that, there’s the simple logistical problem. Even if the galaxy is receptive now, that’s a LOT of people and ships to find, recruit, prepare, and coordinate in just a couple hours of “send[ing] out a call for help for anybody listening.”
There’s perfectly enough time between Ajan Kloss and Exegol.
EDIT: I’m referring to the scenes, not necessarily the locations themselves.