For a long time Canadian Tire could claim that it was the retailer with the largest number of stores. Not any more. Dollarama now has 594 stores.
Dollarama has about 30% of its sales from seasonal items - Christmas, Valentines, Easter etc.
For the past many years, it managed to stick with its $1 price point but now has raised that to $2. It appears to be a good move with ~30% of transactions now coming from higher price points. But at some point, if you push the price points too hard, friends at Bentonville will start taking note of you.