Some people actually do pull out the calipers, resize reference photos and make comparisons between the kit and the references. I've provided photographs to those responsible for assisting with Dragon's M1A1AIM and M1A2SEP kits.
I equate model building to yard work. You might be the type who uses a non-powered rotary push mower and a manual edger. Your neighbor to your right might use a zero turn riding mower and a motorized edger. Your neighbor to your left might hire a landscaping contractor. Neither one of you is doing it wrong, just different. There is actually a member of this forum that "hires a contractor" to do his model building. He just posts the pictures.
When I build some subjects, like WW2 German armor, I'll slap it together straight out of the box. At the most I'll get a turned aluminum gun tube if I can't get the plastic tube seam to disappear.
With a Sherman, I'll probably get a photo etch set because many of the kits don't include the wire periscope guards and other fine details like that.
With a modern US armor kit, I'll probably do some extensive research on the specific vehicle I am looking to replicate. I normally print my own decals to make the bumper numbers for the tank I want. I'll make any necessary modifications or changes to increase accuracy as it suits me.
This thread has degenerated into the reason why I don't give advice beyond "build it out of box and have fun." I'll answer questions about the history of a kit (is it a rebox, how long it's been around, who's repopped it, new tool?), I'll post photos that assist modelers in determining a detail for themselves, and I'll answer some questions about a kit (paint colors included) that I have first hand knowledge about because I have it or have built it.
I've long given up providing any useful critiques or constructive comments at this forum. If you do, even if specifically asked by the original poster, you run the risk of being called a rivet counter, joy sucker, nitpicker, and any other insulting term of endearment by other modelers rushing to the defense of the original poster.