Right frontal versus temporal sharp and slow wave?

When reading on the common average montages, I am often reminded of the quote by WS Gilbert, "Things are seldom what the seem".

Take a look at the following page.

The discharge corresponding to the vertical red line appears to be a sharp and slow wave at FP2-F8-M2-FP1. However, the sharp wave at FP2 may be part of a sequence of waves, while those at F8 and M2 are less clearly part of a sequence of waves. Are they synchronous? 

They certainly are synchronous (see above). Could it not be an F-wave? Let us check it out further.

On the bipolar montage above, this wave has a much bigger field than appreciated on the common average. The probability of an F-wave has increased. For good measure, let us see it on a coronal montage:

What can we conclude? There are 2 possible explanations, namely that it is either a surface electronegative discharge independently over both temporal and prefrontal regions, and less electronegative over the frontal and central regions or it is electropositive over both parasagittal central, frontal, parietal, occipital and posterior temporal regions. The latter is the more likely, I think, for a few reasons. First, the steepest decline in voltage appears between the central and mid-temporal regions (see image above). Second, the vertex (CZ) and central regions (C3 & C4) is precisely where one would find a V-wave, albeit a surface electropositive V-wave. Third, perhaps an electropositive discharge with a large, flat field over the parasagittal central, parietal and occipital regions extending into the posterior temporal regions is more likely than an electronegative discharge over the left and right temporal and frontal regions, remote from one another. Might it be both electro-negative fronto-temporally and electropositive elsewhere? Unlikely, as this would result in much larger potential differences and much larger deflections across the relevant areas. Nevertheless, this is a good example of "Things are seldom what they seem" with common average montages. Maybe one should say, "Things are often not what they seem with common average montages". It took 3 montages to sort it out.