It takes around 1.5 years on average from the time of application to the oath. In case of RQ, it could take up to another 2 years or more. With akka's permanent residency from other countries (US Green Card), it might trigger an automatic RQ according to clause of RQ. And since akka will be residing in US at the time of test, that might trigger almost certain RQ. Since there will be entry to Canada around test date, that also trigger RQ.
As links18 mentioned, if it goes in front of Citizenship Judge, akka will have to prove his/her intention of permanently residing in Canada. Since there have been lot of people who acquired Canadian passport as a stop gap solution on the way to USA, the judge might closely look at this situation. The current government has been touting "Canadian citizenship is not for sale" and has been serious on this matter.
In akka's case, akka was working in US before moving to Canada as PR. Then akka acquires US Green Card and then moves back to US as soon as 1095 days requirement is complete. akka will have some convincing to do to Citizenship Judge if it goes that far. If you have your spouse, children, family or other strong connection in Canada, it might be easy to convince. I guess it depends on case by case basis.
In that past, a lot of people have successfully acquired Canadian citizenship on similar scenario without any problem. But it may or may not be that straightforward in future by just completing 1095 days requirement. Only time will tell.
Also at the time of oath, there should be no doubt about eligibility of akka's PR status. If due to RQ, the whole application process lengthens to 3 years, that might be an issue.
You can request the entry record from CBSA in Canada and CBP in US. But make sure to save other secondary evidences as some entry records might be missed some time.