I’ve never had that issue with my Apple Watch. Granted, apple are a world-class developer (arguably), so their stuff might be more reliable, but I use raise-to-speak and hey siri with my watch all the time.
Recording a note isn’t high friction in my opinion though: “Hey siri make a note XYZ”. Admittedly I don’t create or use notes like this, but I use reminders a lot and I’ve never felt like there was friction: “hey siri remind me to call Dave when I get home”