Switching within a phrase, like “six to 15”, strikes me as pointless hobgobblin-ey consistency, especially when the numbers are close to the cutoff. I find it

Switching within a phrase, like “six to 15”, strikes me as pointless hobgobblin-ey consistency, especially when the numbers are close to the cutoff. I find it so much more jarring than either “six to fifteen” or “6–15.”