rsl12 My hand feels ok I think because the tenths aren't very back to back so you only need to hold that stretched position for a split milisecond and you can also can spring off the keys and turn it into momentum for the next notes. So it quickly relieves any pain or discomfort before it registers.
But I don't have a great understanding of the fast nonstop tenths in stride or Art Tatum style playing. I've tried playing a few bars but when the tenths are so close together, it seems like you can barely contract toward the relaxed/neutral hand position, and have to maintain that stretched position a lot more, then you can't hide from the pain of the stretch.
I don't think it matters too much. I've seen crazy videos of children playing pieces with giant intervals and unless I know the piece I usually can't tell they're rolling it, they're so quick. Even the most famous pianists, some of them also roll these chords.