Different artists have unique and different "workflow" or workflows.
Workflows involve breaking down the art into different stages of development, and possibly different tools.
An artist who has a mature workflow means they have decided on a workflow that balances time, effort, and quality.
Many 2D artists (with moderate to high skill) can use a single program to do all the different stages of their art development, able to use several techniques using the same program. Such programs are PaintTool SAI, Photoshop (lots $, most used), Gimp (Second most used image editor, only beat by photoshop, but this is free, I find gimp can be a bit slow and limited for drawing/painting), Krita, Procreate( 1 time buy, but for iOS or apple ipads), these are the top ones I hear or come to mind.
Many 2D artists may also use a variety of tools. IE PaintTool SAI is really fast so it is great for sketches (or Procreate, or even grid paper if I really want to have fun and control, which I'll scan later), that I can then make a blue print for. Inkscape is for making Vector art, which I like to use the Curve tool with an ellipse shape applied (to simulate a brush stroke) to get highly accurate clean lines, which I can adjust by moving them around without mudding up the image. Krita is also really fast, I like it for its many many brush types, I'll uses it to quickly paint and add details (although I haven't painted in a long while since I like my art simpler and faster, so painting isn't really part of my workflow right now). Gimp has the most powerful layering and filtering system, so I'll paint on different layes in krita, and import them into gimp to do the final mixing. I often want to be able to repose or animate my art (though I have shared any such art), so I will throw it into Blender (I 3D program) and do a bunch of tricks to emulate Live2D (a program that lets you animate 2D art, even works in game engines), so I can repose or make animation of the art.
That assumes you are making art from scratch. Kitbashing is when art tends to be made out of pieces of pre-made art. The 2D community doesn't really do this (since not many share these kits, and they are fixed so unless you are making a character creator they tend not to be very versitile), but in the 3D community, not only is there a special program dedicated to this (Daz3D), but Kitbashing specifically in the 3D community usually means that the parts represent mechanical things, so that you can put together a 3D robot, without having to model all the details, you just need to make a basic shape, and put piping on the outside, bolts, lights, grills, etc.
in the 3D community, there are 3 big names worth knowing. 3D Digital Content Creation (DCC) tools, are tools that make 3D things, Maya tends to be the biggest in the game making industry (professional, industrial), but very expensive. Only those who have used it for years stick to it if they are doing it as a hobby now. Blender is the free equivalent competitor (Just got its 2.81 update last night), and Blender in the past year has racked up a few million in donations for industry giants and huge monthly donators to continue its development, and its paying of, free no longer means poor, as it is starting to compete with Maya, and the programs Disney and Pixar use (even added the Hair shader algorithm used by Disney). I would say Blender is my main tool in the past 2 years because I don't have time to play with 2D art (6 hours for a single sketch, and a total of 12 to have a basic image, and 24 total if I want to have a character animated, not including time for breaks or bed). You can spend a few hours making 3D models, and then once they are made you can just have fun with them as you pose them and make art.
Daz3D may be the most used on this website, it acts like a kit basher as you don't need to make an 3D stuff, rather you can buy character shape models, and clothing assets, poses, animation, sets, etc, and you can add them to your scene, morph and blend character shapes together to get what you want, and clothes will automatically adjust to the body shape.
My current model is to block out 3D characters using Daz3D, import the character and clothes into blender. Use blender to make any edits, and then pose and render out images, and then use a mixture of other tools to try to get a different art style (such as I am experimenting with making an isometric game art style).
If you are talking about games having good quality (3D) art, then those people are probably using Daz3D to make their art (HoneySelect is the anime style equivalent). But if it is 2D, I don't know, I don't see any consistent style across many games unless they have a dedicated artist or are using public domain (CC0) artwork.
The list isn't comprehensive, but it should be a fair crash course in various art programs and tools.
