The notions of wiggling are slightly off, but the principle is valid. Any rig other than those proposed above will cause the boat to turn slightly through the stroke. In particular, since the optimal set up for each rower has them doing more work ahead of the pin, there is a net turning force, which the cox will have to cancel out either with the rudder (which wastes power) or pressure calls (which would either wear out one side (typically strokeside) or 'underuse' the other side). Even in the first case, even though no one would notice the wiggle and could allow it to simply cancel out between the start and end of the stroke, there would still be a slight, avoidable, wiggle, which would waste power (albeit a very small amount) through extra loses from the fin.
As for the advantage, enough crews use these rigs for them to be worthy of consideration. However, this analysis assumes that the crew is perfectly matched. If not, these 'perfect rigs' would need (new) steering corrections to compensate for stroke/bow imbalance, defeating the point of the exercise. Also, having a two+ seat gap between blades on one side may make it harder for a 'sub elite' crew to maintain a good rhythm/pass it down the boat. And we can't forget good old fashioned tradition.
There are also mechanical issues with some of these rigs; the sideways forces are transmitted to the hull, which it must bear. By having 2 or more oars in a row on one side, these forces are proportionately magnified, which I'm guessing would hasten the weakening of the hull. In the case of wing rigged boats, the most pressing issue is practical. In my experience of wing rigged boats, 'symmetrical pairs' (middle pair, outer pair and so on) of riggers are of the same width to match the width of the saxboard at their station, thus only riggers within pairs can be swapped. Thus orthodox bow and stroke riggers are possible; other 'wiggly rigs' are possible (eg. ssbb); but frig rigging would require an extra pair of riggers, at least in a 4 (although it would appear that 'rig d' would be possible...)
The notions of wiggling are slightly off, but the principle is valid. Any rig other than those proposed above will cause the boat to turn slightly through the stroke. In particular, since the optimal set up for each rower has them doing more work ahead of the pin, there is a net turning force, which the cox will have to cancel out either with the rudder (which wastes power) or pressure calls (which would either wear out one side (typically strokeside) or 'underuse' the other side). Even in the first case, even though no one would notice the wiggle and could allow it to simply cancel out between the start and end of the stroke, there would still be a slight, avoidable, wiggle, which would waste power (albeit a very small amount) through extra loses from the fin.
As for the advantage, enough crews use these rigs for them to be worthy of consideration. However, this analysis assumes that the crew is perfectly matched. If not, these 'perfect rigs' would need (new) steering corrections to compensate for stroke/bow imbalance, defeating the point of the exercise. Also, having a two+ seat gap between blades on one side may make it harder for a 'sub elite' crew to maintain a good rhythm/pass it down the boat. And we can't forget good old fashioned tradition.
There are also mechanical issues with some of these rigs; the sideways forces are transmitted to the hull, which it must bear. By having 2 or more oars in a row on one side, these forces are proportionately magnified, which I'm guessing would hasten the weakening of the hull. In the case of wing rigged boats, the most pressing issue is practical. In my experience of wing rigged boats, 'symmetrical pairs' (middle pair, outer pair and so on) of riggers are of the same width to match the width of the saxboard at their station, thus only riggers within pairs can be swapped. Thus orthodox bow and stroke riggers are possible; other 'wiggly rigs' are possible (eg. ssbb); but frig rigging would require an extra pair of riggers, at least in a 4 (although it would appear that 'rig d' would be possible...)