The body is too complex to predict adaptation from training.
This is one major floor with reductionist periodisation that assumes certain adaptation will occur from a certain training method.
Planning needs to be more flexible to allow day to day fluctuations in readiness of all the bodies systems.
One way in which we can have a more ‘agile’ and flexible approach is appreciating the complexity of the body and factoring this into planning. One way in which I do this is by using autoregulation.