There's also a bit of selection bias going on here because we forget about labs that don't have a jump and just focus on the ones that do. Notably Google is definitely not having that capability jump.

Maybe "readiness" is quite a flexible category? You're mid-training for your next model; a rival releases something; you clear the boards and release the model without completing the training run?

Gradual improvements in performance can look like jumps, when you go over critical thresholds.

Combustion engines improved gradually, each year. One year they got better than horses.