I'm sure all those things happened at times, and Ross made to order to some extent, at least for some customers such as Major Blair.
I looked through sources online in the past but found no mentions of big layoffs at Ross until the very end. This was a period when Quebec was arguably still the financial center of the country with lots of industry. Incidentally, hundreds of thousands of Quebec francophones migrated to the USA around this time, mostly to New England states and mostly to work in manufacturing, where they cheerfully and completely assimilated in strange contrast to the Canadian case. The point being that we have no reason to think Ross was a harsh employer or that those who didn't like his employ couldn't easily find work somewhere else.
I don't know if Ross sold through any of the large retailers like Eatons, but he may have had reasons for not wanting to reveal his production and sales volumes through serial numbers at times. Or it could have been a way of subtly recording which rifles he had or had not sold directly from the factory. It might even be that he had a different policy on returns or repairs for rifles sold by a major retailer: they might have been expected to handle that sort of thing, perhaps from their own pockets, whereas direct purchasers were treated differently?? Or more likely, a way to concealing from government eyes how much factory time he was devoting to sporting rifle production rather than his government contracts?
That's all hypothesis and other hypotheses are that rifles that were rebarrelled sometimes did not have their serial numbers added to the new barrels. I'd suspect such rebarreling was done after the factory closure by those smiths who bought up the parts that were left over. Reportedly that continued for a good twenty years or so.
I spoke a credible seeming fellow long ago who lived in Quebec City in the 1960s and early 70s and said at some gun shows there which he attended as a seller he was told by other sellers to watch out for an elderly gent who came to the shows who had a large stock of Ross parts, and to always be very polite to him as "if he liked you" he would sometimes offer to restore a seller's rifle(s) from his stock of new parts for little if any cost.