Lenio,
If you look at it from an current/voltage point of view, the first gen devices finish the entire measurement of a signal, including all averages, until moving on to the next signal (bus voltage for example). This would be akin to the option A you've displayed. The only way to interleave them is to have AVG=1. A potential issue here is that while you are looking at current, any fluctuation on the bus voltage is completely missed until the entire current window is finished measuring. The entire value is held in an accumulator until the total averages are completed.
The second gen devices (226, 230, 231) operate a little closer to option 2 if this is what the customer desires. ZThis figure is from the INA226 datasheet, and shows how the second gen devices have a true interleaved pattern where the data register is still updated only after all of the averages are complete. The difference is that an I and a V are always taken only one conversion apart from another so you are more likely to capture transient variations than in the first gen devices.
Let me know if this answers your question.
