Plan Do Check Act

If  the CHECK shows that  the PLAN that  was implemented in DO is not an improvement, then the existing standard will remain  in place.

In either case, if the CHECK showed something different than expected (whether better or worse), then there is some more learning to be done... and that will suggest potential future PDCA  cycles. 

ACT involves making adjustments or corrective actions... but generally it would be counter to PDCA thinking to propose and  decide upon alternative changes without using a proper PLAN phase, or to make them the new standard (baseline) without going through DO and CHECK steps.

Image description