Do you know why your counsellor continues to mention, teach, and encourage deep breathing as a strategy to support your wellbeing?
Deep breathing supplies oxygen to your brain. This activates the parasympathetic nervous system promoting a state of calmness often called the relaxation response. This is especially beneficial when persons are going through stress and anxiety and have triggered their stress response.
Tips for deep breathing:
Counting your breaths should also serve to take your mind off of your anxiety. If you find your mind wandering back to the source of your stress, try to refocus on counting your breaths.
These times are just suggestions, if you find that, for example, 5 seconds works better for you, then by all means do that. It should be comfortable for you.
If you find that it is not working for you, try slowing it down, refocus, and try counting the steps again.