Challenging incumbent directors

A pessimistic view on this:

"[Shareholders], instead of constantly exercising their franchise, all it to become on all ordinary occasions a dead letter; retiring directors are so habitually re-elected without opposition, and have so great a power of insuring their own re-election without opposition, and have so great a power of insuring their own re-election when opposed, that the board becomes practically a close body; and it is only when the misgovernment grows extreme enough to produce revolutionary agitation among the shareholders that any change can be effected.

As the language may suggest, that's quite an old quote - from an article on the mid-19th century railways, published in 1854. (from this, which looks marvelous). Out of date now, of course, given the huge strides forward in governance, as evidenced by the regular removal of board directors by shareholders...