I thought i would share with you a breathing technique i use to get rid of anxiety and gain energy.
first you breath in for 5 seconds, you have to imagine a flow of energy into your mouth(or nose) and down your body to your sacral chakra (or any other chakra). Hold your breath for 2 seconds then breath out for 7-8 seconds imagining all the anxiety and stress from your body flow out of your mouth. Only do this once or twice, more can be unhealthy.
If you actually count the seconds like that, yes it would be unhealthy to do for a long time. I usually guesstimate...that is, breathe out all the way, pause for a second or two, breathe in all the way then pause for another second or two.
I wouldn't say that counting seconds like he mentioned is nessessarily harmful over time. For instance, one of the most well known breathing techniques in my practice is called the "Four Beat" technique. It involves inhaling for four counts, holding for four counts, exhaling for four counts, pausing for four counts, and repeating. The pausing and counting of seconds is actually useful in that technique, because it can be used to create an altered state. I mean, yeah- don't hold your breath for forever. But still.