(b) Nothing contained in this section shall invalidate a verdict returned by trial jury or an indictment returned by a grand jury when such trial or grand jury includes one or more trial or grand jurors not competent by virtue of such previous service.

(c) Notwithstanding the provisions of subdivision (a) of this section, if the commissioner of jurors, after consultation with and concurrence of the district administrative judge or judges, or in the counties within the city of New York the deputy chief administrative judge, shall determine that:

(i) compliance with the requirements of subdivision (a) of this section would be impracticable, the commissioner may reduce the period of incompetency for persons whose service consists of fewer than three days to a period of not less than two years; or

(ii) the period of incompetency for all jurors pursuant to subdivision (a) of this section may be extended without interfering with the commissioner's ability to comply with the provisions of section five hundred eight of this article, the commissioner may increase the period of incompetency.

(d) Notwithstanding the provisions of this section, the period during which a person shall not be competent to serve as a trial or grand juror pursuant to this section shall be one-half the period specified in subdivision (a) or (c) of this section, as appropriate, where such person so requests on a form to be provided by the commissioner of jurors. Such a request may be submitted at any time during the period of incompetency.