People way over-think HDR, way overshoot way over process. For the most part, Most HDR's can be captured with 3 Images 2EV apart. provided you find your right center exposure.
Most of my most successful and received HDR's have been shot with 3 exposures
But people get into the 3 is good 9 must be better mindset ( and yes I have had to do 9 exposures sometimes) and it really isn't. The more exposures lead to registration errors on complex textures regardless of your tripod (shifts can occur even though your image didn't) and that leads to loss of detail.
Then people overshoot the bracketing and those grossly overexposed and under exposed images REALLY affect image detail. It's hard for the software to find an edge of contrast to align if there is none on that super blown out exposure or that super dark one.
and then people shoot subjects that don't need HDR at all and that leads to just a big Flat Mess of Midtones.
3 works most times, 5 is Good. I've done more when the sun is in the image or shooting an architectural interior with has a huge DR
My 2