It may not be the case. Consider these:
- 20+ years have passed before the struggling Liu Bei established a foothold during the 3 kingdoms era.
- A building spend most of the time laying its ground foundation after which the floors rise up fast.
- Boiling water. Heat & heat like no effect till reach boiling boil then turn from liquid to gaseous state.
- Lift upgrading. Same with building foundation. Digging hole rather long time yet the lift shafts are stacked in 1 day by a crane.
Slowly bit by bit it accumulates. Not seeing any visible effects doesn't mean is not working at times. The boiling water analogy is a good one- trigger point not reached yet.