You misunderstand what he's saying. Because 60 doesn't divide into 7, don't use one 60 minute cron job. Use 7 cron jobs. You could get this magical 7 minute experience over a 24 hour period by creating the following 7 jobs:

0-56/7 0-21/7 * * * Command

3-59/7 1-22/7 * * * Command

6-55/7 2-23/7 * * * Command

2-58/7 3-17/7 * * * Command

5-54/7 4-18/7 * * * Command

1-57/7 5-19/7 * * * Command

4-53/7 6-20/7 * * * Command

Of course, the last job would finish at 23:55, and the next start at 00:00 which is bad. So you'd need to do it on a per day basis. Luckily there are 7 days in the week. So you would just need to write those 7 jobs above on a per day basis. You'd end up with 49 jobs all looking similar to this:

0-56/7 0-21/7 * * Wed Command

Well, you could put multiple cron lines in. e.g. for every 8 minutes:

  0,8,16,24,32,40,48,56 0,2,4,6,8,10,12,14,16,18,20,22 * * * cmd
  4,12,20,28,36,44,52 1,3,5,7,9,11,13,15,17,19,21,23 * * * cmd

This starts to get a bit silly when the interval isn't a factor of 24 though.

I wrote a simple script to generate cron tab specs for "every X minute", and while I enjoyed using gcd and lcm in a real application; something wasn't right. 7 is a very canonical and crazy case because it takes 7 days to cycle. but even then, it doesn't work with months except for February for non leap years.