American here that does long haul drives rather frequently for dog shows…
When I give a time, it’s without breaks. “10 hours to the Fairgrounds” - 10 hours of straight driving with no problems.
I tell folks new to my methodology to anticipate around an hour of variance for every twelve hours, as I typically must stop 2x for gas at least. (My tank holds 400 miles / 12 gallons, and I try not to let it drop below 50 / 1.5 gallons.)
For the dog shows, I’ve got a varying number of dogs with me (8 was my max, 2-4 pretty common) and pottying them takes forever.
Edit for Clarification: I’m content to drive around 14-16 hours straight without stopping to rest. If the trip is longer than that, I do have to pull over to nap.