This is one method. I would echo the need for a good warm-up first as if you're anything like me your HRM will be all over the place for the first ten minutes. The idea of running for three minutes rather than over a set distance is because the effort you put into a distance depends on your fitness - 1k is very tough for some people, so they'd go at a lower effort in order to complete it.
(3 mins also curiously echoes Billat's original VO2max training.)
Go with some of the advice in your previous thread? Do a MHR test to see if 192 is really you, then decide. If it is, and you want to train by HR, then it's ok from time to time, but within the boundaries of a controlled training plan.