Overall:
There is minimal indication that submitting anything other than what is specifically requested will help.
An extra few documents probably does NOT hurt, but if the documents contain inconsistent information, obviously that could hurt.
A lot of extra documents not only increases the risk of some inconsistent information in the content, but also risks raising some questions about (1) why the applicant has not simply followed the instructions, and (2) whether the inclusion of extra documents suggests the applicant is aware of some reason to question the applicant's physical presence, and if such reason should cause IRCC to elevate scrutiny of the application, perhaps issue RQ.
We know for sure, at least based on historical reporting including what has been revealed by internal CIC memos (before transition to IRCC) that RQ can be and has been issued to applicants despite the submission of extra documents to prove presence in Canada, including some instances in which the applicant included most of what is requested in RQ . . . in which cases, the applicant was required to respond to RQ despite already having submitted almost everything the RQ requests.
Some further observations about submitting extra documents:
It is highly unlikely that a small number of additional pages/documents will negatively affect the processing of a citizenship application UNLESS the content of those documents raises an issue (such as revealing some information inconsistent with what the applicant has provided otherwise . . . NoA showing applicant's address different than the address for that time period provided in the address history for example).
Many, many, many have reported including some extra documents with their application with NO apparent negative effect at all.
Me too. That was some years ago, now, but in any event I included extra documents, my NoAs for four years, and my timeline to the oath was way less than half the timeline CIC was reporting at the time, and within a close margin of the faster timelines being reported during that time period. I had very specific reasons for including the extra documents, related to my personal circumstances (related to same reasons for waiting to apply nearly two years after I passed the threshold of eligibility, in large part related to being self-employed and providing services for foreign clients). In this context, remember that the median timeline for citizenship applicants has tended to be way less than what IRCC (and before it, CIC) reports as the timeline, and in particular, when the reported timeline has exceeded 14 months or so, most applicants appear to reach the oath in around or less than half that reported timeline. The disparity between the reported timeline and median (which in practical terms means for most applicants, albeit most by a small margin) shrinks considerably when the reported timeline is around a year or less, which statistically makes total sense given the much lower deviation range.
On the other hand, there have been no more than sporadic reports that including extra documents has had an apparent positive effect, and those few reports tend to lack verification of a cause and effect relationship. (Note, for example, some might infer my inclusion of NoAs did help my processing timeline, since I included them and I had a fast timeline . . . but there really was nothing about how my application went through the process which indicated my NoAs helped.)
As already noted, there have been scores of examples where it was readily apparent that the inclusion of extra documents, even a lot of extra documents, did NOT help the applicant avoid non-routine processing, many getting the full-blown RQ despite having submitted a lot of proof as to address, work, and other activity history in Canada.
There are circumstances in which additional documentation may be a good idea:
Applicants who recognize that certain information in their application might be confusing or misunderstood, or might appear to be incomplete, or is incomplete, or otherwise needs clarification, can and in some instances should include supplemental pages to complete or clarify that information, and this may involve including some relevant documentation beyond those documents specifically requested.
This does not apply to the vast, vast majority of applicants. This really is about unusual circumstances. This is in recognition that there is a huge, huge range of variability in personal circumstances, that there is no one-rule-fits-all approach.
Applicants should approach including any extra documentation cautiously and carefully, giving due consideration to why they believe including the additional information or documentation is NECESSARY (not merely helpful . . . if it is just helpful, that weighs in favour of NOT including it) and then being very judicious about what is specifically included, leaning toward minimizing the quantity.
Of course, if it is necessary to utilize additional pages to completely answer any item in the application, the applicant should do so. But, in doing so, to focus on providing the information requested and little if any more than that.
Indeed, in general it is better to respond fully to IRCC requests WITHOUT providing more than a complete response. This can be a bit of a balancing act in peculiar circumstances. Additional information to clarify is OK. Additional information to complete an answer (as in an answer that would otherwise omit material or even relevant information) should be provided. But ordinarily there is little or NO reason to submit additional information to corroborate or support an application.
Caution for non-routine processing requests:
Applicants will want to lean the other way when responding to CIT 0520 (RQ-lite) or CIT 0171 (full blown RQ)
In general there is little need to go overboard when responding to non-routine processing requests, including either version of RQ. In the past I have cautioned against dropping-document-bombs, even in response to the full blown RQ.
But applicants issued a version of RQ, for example, would be prudent to err on the side of including too much rather than too little. Minimalist responses to RQ can lead to serious skepticism and a full blown presence-case, meaning long delays with a risk of the application being denied.
For any applicant issued either version of RQ, include additional documentation if it is reasonably within the scope of what is requested, and be very careful to avoid failing to include something which is even merely arguably within the scope of what is requested.