I do use two mirrors too. After conditioning and still wet, I can make straight cuts and even gradual rounded cuts from around the ears to the back. This was hard at first and a good stylist would likely do a far better job of having all of your hair match your face and style desires. But if you simply do not want your hair to get really long and have a pretty consistent look from your last trim, after months of practice and using professional cutting and thinning shears, you should improve from making some miscuts to doing a fairly decent job.
I rarely cut my hair when it is dry to adjust the length, except from those random strands. I do use the thinning shears when my hair is dry for the simple reason that I want to see how thick the hair looks as I make each thinning cut. The thinning shears has those notches instead of flat blades, so it will not cut all the hair between the blades.
My hair in the back can cover my collar for sure and hangs down straight and is thick. I am presenting as male but if it does get thicker and longer, I would think some people might consider it unisex or even fem, because even now, it can have a rounded, close to same length thick look from the back view when it is fresh and clean.
Because of a medical condition I have used Fin for years. It has an amazing impact on my head hair. As a male, it is probably counter gender to enjoy noticing my hair "moving" in the back as I turn my head. I think if it was just as long all around my face, covering not only parts of the ears but all of the ears and my cheeks, I might enjoy playing with it a lot as it moves across my face and I might have a lot of trouble focusing what I am doing. Maybe not, as women have to deal with that a lot. It is just a necessary part of women having that hairstyle, and they certainly go on with all their important activities in life.
While I am a guy I might have some T like thinking. I am learning a lot here. I just do not see myself with GD at the moment. Perhaps just different or more inclusive in thinking.