Also those who make money and those who don't. If you are shooting for a paying client It is best to think ahead and get the shot they need.
If you are doing video and the shot involves other people you had BETTERhave you act totes long before or yu annoy the crew and talent.
Then there was Ansel Adams and others like him (who I think were better, Like Weston and his sons. Adams used to write about "previsualizing" the image. He always knew the result he wanted and would some times have to wait months forth wethers and lighting to be what he wanted
Yes I've done the thing where you take a camera ad hope for an opportunity. I've done a fair amount of underwater dive photos But still I have an idea of the kinds of photos that are possible and what I will ignore. The previsualizing thing even works when jumping into an unknown environment. I tae the off camera lighting equipment needs for the kinds of shots I'm looking for
Same even for family snap shots. I know in advance about the kind of shots I want - environmental portraits or my daughter. Go I select the 85mm f/1.8 lens and go out on a cloudy overcast day. IF the light was not right (to sunny) I've either leave the camera at home or shoot some other kinds of images. Likely leave it home as my daughter would be along.
SO in short for almost all commercial work you do likely have exact compositions in mind and even for what look like snapshots, they come out better if you already know what light you want, what kind of DOF and colors and then you keep your eyes open for shots that are on your list Even photo journalism an sports is like this. If shooting gymnastics or snownbording you wait for the shot you have in mind.
I agree with your comments in this post and (to a lesser extent) your previous one. I don't do paid work (though I have shot events for friends). For my landscapes if I'm going back to a spot I've been to before I think about what shots I want to get and pack accordingly. What focal length (or focal length range) am I going to need to get the image I'm thinking of? What filters and what strength of ND filters are going to get me what I want?
Even for outings where I'm not going to be shooting from a tripod, what is the one lens that I'm going to mount before I leave that will get me what I want for where I am going?
For example, if I am going to a zoo I pick one of three lenses if it's going to be an "animal" day: 100-400, 70-200 f/2.8, or 70-200 f/4. If it's going to be a "people at a zoo day": 24-70 f/2.8 or 50 f/1.4 or 55 f/1.8. Rarely I'll take one of the longer lenses and throw the 55 into the bag "just in case". But I've never actually switched lenses at a zoo. I get into the zone with the lens I have mounted and find the compositions that are appropriate for that lens.
This same principle applies whenever I leave the house: what am I expecting to see and what images am I expecting to walk away with? Yes, you have to be open to whatever opportunities present themselves, but you either have a photographic agenda (and pack accordingly) or you don't. In the latter case you still have to make choices about the gear you bring....
Back to the OP.
I switched to Sony from Nikon (with a Leica M stop in-between).
I prefer my Sony (currently A7R III with an A7R II now serving as a backup body). Why?
While I agree that the overall weight savings aren't great once you start attaching fast zooms, the body itself is still smaller which affects bulk--even with a long lens you can get away with a slightly narrower bag. Minor point, I know.
The real reasons I prefer my Sony's over my Nikon D810 are lots of little small things that add up to a better package for my needs.
I like the in-body image stabilization. Works with any lens. Useful when shooting handheld.
On the A7R III I love the thumb joystick that makes it easy to change the focus point (as opposed to the A7R II).
I love eye AF (especially with Sony lenses that have a button on the lens to activate this). The A7R III is better than the A7R II in this regard. Eye AF works really, really well. Obviously only matters for people pics, but I use this all the time. It nails focus on the eyes and holds it even when you recompose. I don't post pics of my son or other people here, but it is a decent chunk of what I shoot now. Eye AF is awesome if you shoot a lot of people pics.
No need for lens calibration. Many of my Nikon lenses were slightly off in focus on my D810. Was a PITA to manually calibrate them. For my Leica Ms I would test each lens on the body and then have to send the body and lens off to Leica to have them calibrate them. It got old really fast. In the end with my Leica M I would only shoot using an external EVF--which added bulk (specifically height) to the camera which required a bulkier bag and the external EVF had crap resolution.
The Sony flash system is really, really good. Better than the Nikon flash system in my experience. TTL flash works remarkably well and I don't find that I *have* to shoot in manual flash mode to get the results I want. It is also really intuitive and easy to adjust. They are the first flashes I have used that I don't have to pull out the manual if I haven't used them in a bit. The newer flashes are all radio and easy to use off camera. The commander unit (either a flash or a non-flash commander unit mounted on the body) are *really* easy and intuitive to use. Easy to set settings on the remotes from the unit mounted on the body. It's very Apple-like--it's intuitive and it "just works". Both TTL and in manual mode. For much of what I am currently shooting, this matters to me. Flash photography is challenging, though the results can be game-changing. Having gear that "just works" vs gear that you have to fight with can matter. This is obviously subjective and if you use flash daily you quickly learn how to make the adjustments you need with the flashes you have. But for me at least, the Sony flashes are a pleasure to use rather than a hassle.
Ultimately I'm happy with my Sony because it does what I need it to do in a way that works for me. The total system does what I need it to do better than either my Nikon D810 or my Leica M.