I can hook up to my bumper pull trailer in 5 minutes solo and that includes busting the stinger out of my horse trailer and putting it in the pickup. Your 20 minutes is right for when I first started but not now.
I use a 2" drop, non adjustable stinger for the bumper pull and have a flip up ball for my gooseneck. If I was pulling multiple height trailers then I would get an adjustable hitch.
Not sure if this is some of the information you are looking for but you select your drop height so that your trailer is as level as possible when hooked up to your tow rig. That of course will be determined by how tall your pickup is, how much it squats with the trailer hooked up and how high your trailer is.