How to best schedule AO and MI for learning

When using action observation and motor imagery in combination for motor learning purpose, the scheduling of AO and MI is still an open issue. How should we schedule combinations of AO and MI to get the best out of it? And why is this the case?

Taeho Kim’s most recent work as part of his PhD project was just accepted, comparing simultaneous, alternate and blocked combinations of AO and MI (Kim, Frank, & Schack, accepted; to appear in The International Journal of Sport Psychology):

The results of this study showed that the three different AO+MI training
improved mental representation structure and skill performance. In particular, the effect of alternate AO+MI training was relatively stronger. Taken together, the findings of this study suggest that simultaneous, alternate, and blocked AO+MI can be used as effective training schedules for enhancing the learning of a sequential motor skill, among which alternate AO+MI training schedule may be more effective.