How was she even attempting to do this when Canadians are limited to 6 months per year in the US?

AFAIK, it wasn't an arrangement she'd been in for a long time. I doubt she'd hit the six month point, and had been hoping to secure a visa to stay in the country legitimately.

Ack.. that's just incredibly poor judgement. If you have to lie to the officials when entering the country, you really shouldn't expect that a closer look later on is going to get you a visa - as soon as they discover you lied about it you're done for.

It's pretty common to lie to border agents. Both US and Canadian agents themselves have advised me to do so in the past. Ticking the "Have you been on a farm?" check box triggers a compulsory search for seeds (both smuggled and inadvertently stuck to your shoes). It is time consuming, and they know it to be a fruitless waste of time.

Canadians don't need a visa for tourist visits to the US, and passports aren't stamped on exit. It's an incredibly BAD idea in my books, but it's still probably relatively easy for a Canadian to spend a whole lot of time in the US without getting flagged.

Having been here (legally) for 17+ years, I would concur that there is absolutely nothing that would prevent a Canadian from living/working here, other than their integrity and respect for the law (which, admittedly, Canadian have in abundance) - Well, that and a desire to return home for free medicare, more generous welfare system, ... :-)

The only evidence I have submitted to a half dozen employers of my right to work in the United States (because it's all I've ever been given) - is a cardboard I-94, filled out by me, no less, with a faint, blue stamp and date, and a (once again handwritten, this time by ICE agent) "Class: TN, Until: 07 Oct 2015". No Serial Number, no tracking number - just a stamp and visa class.

You do realize that your TN status is only for a single employer, right? You must obtain independent TN status for each employer you work for. Showing an old TN has no bearing on your eligibility to work for someone else - you must reapply.

Not trying to scare you, just noting that I have had at least one friend on TN's who tried to bridge their status without filing a proper change in status ( ie. to B-2 as soon as you quit/are let go from your old employer, to be eligible to stay without packing up your apartment) and were banned from re-entry for 2 years.

I have had several TN's over the past 16 years and the only trouble I have had was primary border guard overreach once or twice (they felt I had been in the USA long enough, arbitrarily. Secondary review fixed that.)

Yup - intimately familiar with the "Must obtain independent status with each employer". Every time I change an employer, new trip to the border to get a new TN.

I did not realize I could file a change in status if my old job concluded before I got a new one. In 2003, I finished up with a company, and my last, "Paid Day" as an employee was September 26th, but I wasn't required to come into the office for the last two weeks - so my last day in the office was around September 12th, a friday. By Sunday, September 14th, I had emptied my apartment, packed up all my possessions, and had returned to Canada.

Depends how much you travel. And if you have proof of employment in Canada.

Returning to Canada after an extended stay and then returning to the US, you will almost always be questioned.

Stamps are old school, they log your passport or NEXUS on each entry/exit in their system.

On exit? They don't even look at my passport on exit.

How did she work in the US without a work visa? Every company that I have worked for (large and small) do the I-9 verification process at the start of employment. I can't see any company being so desperate for employees that they would skip that and hire someone without work authorization.

Of course, if you were working for yourself (freelance), there are no employment verification checks.