Wanted to get an idea of how common it is. Does it happen all the time or on pretty isolated cases?
For the last few years there has been rather little anecdotal reporting of RQ-related requests for additional information, and most of that has not been full-blown RQ.
In contrast, however, there have been more indications that when IRCC has RQ-related concerns or questions, the application is handled in a RQ-related non-routine processing stream that involves more extensive inquiry and can potentially result in a referral to CBSA's investigatory branch to conduct a more thorough investigation. Since investigatory processing is confidential, applicants are not informed of this directly but many can discern it due to the timeline, a significantly longer timeline.
There is less uncertainty in the process of verifying physical presence these days than there was a decade ago when being "
RQ'd" was more frequent. The biggest difference is that there is now an actual physical presence requirement compared to the residency requirement back then. But the expansion and improvement in CBSA capturing and storing client travel history has also had a big impact, dramatically improving the extent to which IRCC can verify most if not nearly all the travel history reported by citizenship applicants. Meanwhile, the extent to which just living in Canada results in a digital trail which can be more easily cross-checked has also dramatically reduced the extent to which IRCC cannot readily corroborate an applicant's address and work history, further reducing the need to ask for additional information in regards to the applicant's presence in Canada.
The best approach to avoiding RQ-related non-routine processing, which can cause quite lengthy delays, is to be as complete and accurate in all the information submitted as possible, and to submit an application that fully shows the physical presence requirement was met; for this, a good buffer helps, how much buffer depending on the particular individual's situation, for some it being prudent to wait to apply with a bigger buffer.