You are looking for answers to a question that I'm almost certain nobody actually knows, unfortunately. I mean if you know anyone that works at the mint they MIGHT be able to find out but my guess is sometimes in the early 1980s to 2000s the RCM
started using the single squeeze method.
2006 5 Cent nickels for example were subject to master die doubling produced by using the single squeeze method.
Through all of my documentation, studying and research regarding doubled dies on every denomination of modern Canadian coins from 1940 to 2021 there was an abundance of doubled dies on each denomination up until 1979, doubled dies became fairly uncommon until around 2012 and the designs became more "generic" looking.
Prior to 1979, you could tell that the mint used different methods (older style) because the designs, details, and even the beads/denticles around the rims had minor imperfections, as soon as the 1980s hit everything turned dull, and again, generic looking.
If I were to take a wild guess these would be my estimates...
Pennies - 1980 to 2012 = Single Squeeze
Nickels - 1980 to 2021 = Single Squeeze
Dimes - 1980 to 2021 = Single Squeeze
Quarters - 1980 to 2021 = Single Sqeeze
Loonies - 1980 to 2021 = Single Squeeze
Toonies - 1980 to 2021 = Single Squeeze
Long story short, to me it looks like sometime in the 1980s is when single squeeze became the norm, but again these are only guesstimates.
The single squeeze method was supposed to get rid of the chance for doubled dies to happen, however, it actually made doubled dies even more interesting.