Even if the record is completely blank, I would highly recommend fulfilling the CIC request as it shows that the applicant is following instructions in good faith, providing requested documentation and acting in an open, transparent manner.
Personally, if the CIC did not request the document from you, I wouldn't recommend getting it. There is little use in borrowing tomorrow's problems for today and trying to outsmart the CIC and the wait times. If they request it, you can get it to them as quickly as possible. Even though OHIP will probably not be able to meet the 30 day deadline, this is not your fault and your citizenship will not be denied by one government agency due to the timelines of another government agency (assuming you place the request in a timely manner).
Regarding the value of this document for applicants who have not seen the doctor often, if they ask for it, just provide it (assuming you have no moral or privacy problems with providing it), rather than trying to judge rather they really want it or will like what they see. Even if you just went to the doctor once, that will show something. Personally I'd still recommend sending it as a gesture of goodwill and transparency even if you didn't go to the doctor at all.
Good luck.