I use dual wave much more than square wave, but to do the same thing.
Large meals – over about 60g carbs I would do a dual wave. If I did square wave over an hour I’d be high as I wouldn’t have enough insulin in early enough. I’d generally do 50% of the insulin up front, then 50% over the next hour for something like pasta (those timings assume you start the bolus about 20mins before you start eating, so the last of the insulin goes in 40mins after you started eating). For pizza, I do 40% upfront and 60% over 2 hours.