Let's have a little pause for thought about TAs and why they are what they are. The idea is that you can fly on standard setting without bumping into cumulogranite, whatever the temperature and MSL pressure. The US with its Rockies at 15,000' needs a TA of 18,000'. We have the Alps in Europe, but not as big. But other countries don't need such TAs. Even Spain at Menorca has a 'normal' TA. France, UK, Germany, Italy..... all 'normal' too. But having a high TA like 18,000 or 24,000' is a plain PITA- needing QNHs reset constantly as you move altimeter setting regions when below TA. Maybe they need it like that in the Mountain area, but the coastal regions and Central? An 18,000' TA is a nonsense.
Indeed, it is the US/Canada that are the oddities, and frankly, I didn't like it. Coming late like that, it is too easy to forget to change over well into the climb when things have gone quieter. Changing early, it is usually wrapped up in the After Take Off check as well.