The reason the OL stations are so deep along Queen St is exactly because they are not using this method. Osgoode and Queen will instead be in the bedrock which removes the need for underpinning but makes the stations fairly deep. You can even see with the designs for both stations, they avoid digging under the existing stations until it's within the bedrock. (which is why in the one diagram of Queen station there is a volume of soil below the current station and above the OL station, with the escalators on either side of that) Almost certainly, this is as you suggest, a reaction to the schedule issues with underpinning on the Crosstown.This video is from 4 years ago, explaining the underpinning being done under Eglinton Station for Line 5. Bet this is why everything is s-l-o-w in completing the Line 5 stations. Why don't they just say that is the reason we are so behind.
Guessing that they will NOT be using this methodology to build the Osgoode and Queen Stations for the Ontario Line. Unless they are very, very quiet about it.
The reason the OL stations are so deep along Queen St is exactly because they are not using this method. Osgoode and Queen will instead be in the bedrock which removes the need for underpinning but makes the stations fairly deep. You can even see with the designs for both stations, they avoid digging under the existing stations until it's within the bedrock. (which is why in the one diagram of Queen station there is a volume of soil below the current station and above the OL station, with the escalators on either side of that) Almost certainly, this is as you suggest, a reaction to the schedule issues with underpinning on the Crosstown.