If you are talking about on the watch, I actually love this for stopping workouts in the winter, when I am wearing gloves. Starting workouts is easy enough without Siri. I may quibble, though, with it being faster. Siri doesn’t always respond quickly in my experience, and you get the occasional “I didn’t quite catch that. Can you say it again?”
As far as Siri on the watch, I love it for starting cooking timers, as you can have multiple timers going with labels if you start them with Siri. “Hey Siri, set a 7 minute lamb chops timer” while you already have a “Hey Siri, set a 25 minute rice timer” going is very helpful.
I’ve done this for a long time. Living in a hot climate (Brisbane in Australia), I often ask Siri for the temperature, humidity and “feels like” (perceived temperature) as I run and sweat (a lot!)
Relatedly, when I’m running or cycling, asking Siri to read my messages aloud is very helpful. I’m sure there is much more I could do.