I tend to keep my hand on the regulator as I am using my oxygen and adjust it up and down as needed. I try not to let the bag overfill to the point the oxygen is coming into the mask before I am ready for it. I change my breathing up almost hit to hit as needed. Sometimes long deep breathing works and others short faster breathing helps me better. It kind of depends on the situation and how fast I get to the 02 tank and get started. I will also chug down a 5hr drink to give the 02 a jump start, grab an ice pack and find a effective pressure point to apply that to it, Also changes per hit, and adjust my seating position. I am a sitter not a walker so stretching out my back or doing a crunch or both will change the effectiveness of my 02 sessions.
By the end of the party I am breathing at a normal rate at maybe 4 or 5 lpm on the regulator.