Unless doing an AC-AC connection doesn’t one have to collect and re drop their bag in YUL? Even when coming from the EU?

Same line for declarations or not. Download the app to complete form on the way and save a few mins at kiosk. Be honest, unlikely to take long unless planning on important fresh meat or veg etc...

Even with bag recollection should be quite quick. But not 5 mins, if on time 80 mins is fine. Lounge can be a trek from your gate though ... and you’ll clear security again as you can’t go straight across unless that’s changed recently...