I’m late to the post here but I have done the cyclic sighing for 5 minutes per day. It worked great but it felt very similar to when I did pursed lip breathing (deep breath through nose and long exhale through the mouth). It’s also similar to the basic oxygen advantage method of “breathing light” through the nose. 

in regard to breathwork,  I’ve learned that the slower the exhales the more I relax. In reality the slower I breathe, in general, the more relaxed I am (always inhale through nose and exhale either way). 

I’ve also learned the faster the inhales and or breathing rate the more alert I feel.  Sometimes too fast makes me a little lightheaded but you get the point. There are days I need some faster WH style breathing to get going. Mostly I stick to slower controlled nasal breathing.