very slow breathing while running

OK, so I have made a commitment to improve my run over the winter. So to avoid injury and just log a bunch of miles I am using training based on heart rate, most notably using the Maffetone Method. So with this method I am supposed to be running at or below roughly 140 HR. When I first started I noticed that I would hit this mark quite quickly and have to walk for a short stint to get back below 140 then start light jogging again. I noticed taht running under 140 kept me injury free for the entire second half of my training this year, so I am sticking with it. My question is this though......... After doing this method for awhile now I have really come to notice that even if I run at the same exact speed for a certain period of time (easily duplicated on the treadmill using the same speed) that I have a ton of control over my HR just by adjusting my breathing.

If I breathe every other step or even every 3rd or 4th step, my HR tends to drift up faster than if I take really long deep breath's. When I say long, I am talking about breathing in over the course of 6 sometimes up to 8 steps and then slowly breathing out on 6 to 8 steps as well. When I do this, I can slow watch my HR drop and then stay at a much lower rate than if I breathe quicker. Is there anything wrong with taking such long slow breath's? Should I really be using my breathing THAT MUCH to control my HR? Might be a stupid question, I might just get the answers of "breath however the heck you like". Just want to be sure that i'm not doing any harm by using my breathing so much to suppress my HR. Thanks in advance