2qwerty
“Most litvaks don’t avoid making kiddush from 6pm to 7pm.”
Its a bit strong to call this halacha. And you probably dont mean 6pm to 7pm since that doesnt really make sense. 6pm to 7 pm worked prior to the advent of Standard time in the late 19th century. Since the advent of Standard time it remains 6-7 pm haalchic time or mean solar time which in NY is 5:56-6:56 (with DST it is 6:56-7:56). Admitdly not much of a difference but In Yerushalyim it is 5:39-6:39 See Yisroel Vehazmanim chapter 27 for details. (this is the most common way to calculate it the less common ways are to avoid during the first hour of shabbos regardless of what time is on the clock another way is to take the sixth hour after chatzos of that day (this is similar to the first more common method which takes 6 hours after the average chatzos )
A blanket 6-7 pm avoidance doesn’t really make sense
I do like the bentching al kos example