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The provision in SDPWS 4.3.2.2.(4) that collectors are required throughout the full length of the FTAO wall refers to the transfer of forces from the diaphragm to the shear wall, not the internal transfer of forces around openings via blocking and straps. A continuous collector is necessary because the shear force distribution to FTAO piers creates differential forces in the top piers of the wall, and axial tension and compression forces build up in the top plate of the wall, which acts as a collector dragging or pushing the uniform shear force from the diaphragm above to the piers below.
Shearwalls reports these drag strut forces at the same locations drag strut forces appear for segmented walls, that is, the sides of each opening and at the ends of the wall where there is a gap in the shear line. These locations are where the local maxima and minima of tension and compression forces occur, and these forces vary linearly between these points.
The mechanics for these forces is different than for segmented walls, however. For a segmented wall, there is no shear resistance in the sheathing above openings, so that the drag strut above the first segment with an opening drags additional force into the segment to the left, and pushes additional force into the segment at the right, typically creating tension in the drag strut at the left side and compression at the right.
For a FTAO wall, the shear force in the sheathing above the opening is typically greater than the corner pier forces, so that the drag strut pushes additional force into the pier above the first opening from the left, and pulls it into this pier from the right. This typically creates compression in the drag strut at the left side and tension at the right.