The commissioner may extend the 6-month period provided in section 511(1) once, for not more than 90 days, if the commissioner determines that a health care corporation requires additional time to assess the findings made by the commissioner or to prepare a provider class plan that substantially achieves the goals, achieves the objectives, and substantially overcomes the deficiencies enumerated in the findings. In making a determination under this section, the commissioner shall consider the number of provider class plans, the extent of the changes to each plan, and the stage of development of each plan being prepared by the health care corporation pursuant to section 511(1).