Every time I was oncall during weekends or holidays (or outside work hours) it was just a normal day with the occasional "phone call". As long as I had my laptop with me and I had some kind of network coverage (which I did unless I went trekking in the non-existing mountains of Ireland, which I didn't during oncall days) it was fine.
My coworkers in search or ads were a bit more stressed out on that though, I agree, having to ask their secondary to cover just for the 5-10 minutes they wanted to take a shower because they could not miss a single alert, but for us on a secondary service that was not a problem. I've had days where I commuted by train (40 minutes ride) with spotty internet and 0 problems because having a 15-30 minutes response time meant that I had enough buffer to get off the train and find some place with wifi with plenty of time to spare.
> I definitely consider every hour of the day I'm on call (all 24 of them) as a working hour
You'd be incorrect. We also don't do 24 hours shifts.