Before I comment on anything by commuting I meant going very frequently like may be 2-3 times a week or even 3-4 times a month. A less than this number could be fine. Better to stay they M-F and back for the weekend.
There are several reasons: the biggest one is the immigration offices at the border create a lot of issues and can deny and have denied entry due to frequent traveling. Frequent crossing creates a red flag with the immigration offices.
In fact with this type of entry exist a cousin of mine who is a US green holder for many years was strictly warned that they will deny his GC at their will and asked him to not do this frequent broader crossing and (he then moved permanently to the US).
2nd if the crossing is very frequent you are inviting trouble with Canadian immigration and can jeopardize your future with Canadian citizenship. They keep an eye on your intention.
Better is to stay put until you get your Canadian citizenship.
Your cousin would have been a PR in Canada as well as GC in US hence the issue. You cant make both country a primary residence to show the respective country that you are trying to settle permanently.
Definitely not all officers on both borders are comfortable with. My friend who mentioned India address as permanent address by mistake was warned that if he wants to give up gc. So surely the gc candidate's intention should be to make the US a primary residence, not some other country.
So above situation is not comparable with the situation i mentioned. Here the candidate is on H1 and will be PR on canadian side. Both cases are totally different. We are commuting for years without a single event on retaining immigration status. So you can broadly tell that commuting is bad idea.
No red flags in commuting. One of my directors crosses border on commuter gc for years. No issues. We all commute on H1 for years. No issues.
Intention clause for canadian citizenship is gone few years ago itself. I agree that one should stay inside till citizenship but its not practical/economical & unnecessary for most to give up job at the border and move.