Yes that seems like the situation here. The so frequent travels to US is taking up time for background check.Actually, I do think that the more travel you have outside the country the longer it takes to complete their background checks and cross referencing.
I'll explain why I say this. Hubby traveled only twice across the border in the entire period in question. I traveled about 5 times. Sometimes they were flights out and other times were driving across the border. Now, where I drove across the border they didn't stamp my passport so it was up to me to ensure I recorded my leaving and return trips diligently. I also made sure I returned that slip at the border every time to make sure there were no issues in proving my departure and return.
During my interview, she went through my passport and identified all the entry and departure stamps and queried some dates I had put on my calculator but were not present in my passport. Luckily I had the trips well documented and could actually tell her which ones she would not find stamps for and which ones she would. She cross referenced and checked off all the dates.
Another thing I did with my application was if there was a gap anywhere, I included a note that explained the gap or any discrepancy. I've learned over the years of dealing with the Canadian government that they do not like grey areas. So if you take a look at your application objectively and some dates or occurrences are not making sense or don't add up to you, chances are they will have questions. So just explain where required and you might save yourself some time.
Hang in there though, hopefully you will see some progress soon.
Thanks for giving the hope, and Congrats on your upcoming oath ceremony!!