not every single time, i have been working for the bank 12 years, and i have seen all sorts of fraud attempts, 90% of the time, either employment letter looks suspicious, t4 2019 and paystubs dont match , or there are many inconsistencies, but i have seen pretty good attempts as well. if we have doubts we do call to verify.
i am going to say something here, if you are willing to produce falsified info, you should be ready for the consequences, a lot of times the broker is crook and assist the client (with a lot of cash fee) the make these, maybe somehow you get this mortgage, at one point in time that crook broker will get caught, and the bank will look at that person's deals they have done and went through all, don't be surprised one day the institution calling you to verify and give you a 30 day notice to find yourself another bank for your mortgage.
it happened and it will happen. i have seen a person who got a mortgage from a major bank and then 6 months later got a letter saying they have to find another institution in 30 days, you either will have to find a bank or small lender, as be ready for the exorbitant interest rates these places will offer. that person ended up being forced to sell his place.