When should I use MVT instead of A/B testing?

Choose MVT over A/B testing in specific situations:

Large audiences where you have enough recipients to achieve significance across many combinations. Typically this means hundreds of thousands or millions of subscribers.

Suspected interactions where you believe elements affect each other. If you think subject line tone should match body copy tone, MVT can validate this.

Holistic optimization when you want to find the best overall email rather than optimizing piece by piece over many sequential tests.

Mature testing programs that have exhausted obvious A/B improvements and need deeper optimization insights.

Avoid MVT when audiences are small, when you need quick answers, or when you are still learning basic testing methodology.

MVT is the advanced course. Take it after you have mastered fundamentals and have the audience size to support it.