When configuring Motiva Message Testing AI, there's an option called Confidence Threshold.
If the confidence of a particular variation reaches the confidence threshold, Motiva will automatically invest all future sends in that “winner” and stop sending other variations.
The default is fairly high at 95%, but if you prefer to can select a lower value - either 90% or 85%. With a higher the value, you can be more confident in the "winner", but it will take longer to find.
Also see Confidence.