I have, over time, re-aligned my manifold several times when I have worked on the table, but only for asthetic reasons. Again, if you use the alignment pin to anchor the right end of the overhang guide, then what you're saying is correct. I am just pointing out that it is possible to not anchor the guide with the pin and, although it is slightly trickier, you can align the overhang and tangency by swiveling the alignment guide, anchored only at the spindle end, at the same time as moving the cartridge on the headshell until the stylus is aligned all the way along the line, while keeping the alignment guide stationary, once you've found the appropriate position. Although this is evidently tricky to communicate, it is quite easy to do and precludes having to make the adjustment you're talking about.
Sorry to invoke such long winded confusion. I just thought it was worth mentioning.
Sorry to invoke such long winded confusion. I just thought it was worth mentioning.