Dialogflow CX uses your training data to build machine learning models specifically for your agent. Each flow of your agent has its own model. This training data primarily consists of intents, intent training phrases, and entities referenced in a flow.
There is two types of ML training:
Standard NLU and Advanced NLU .
The standard NLU type has a setting to enable or disable automatic training.
The advanced NLU type does not support automatic training.
If you have disabled automatic training, or the NLU type does not support automatic training, you must execute manual training after you have completed updates.https://cloud.google.com/dialogflow/cx/docs/concept/training#draft-auto