I Can Just Fix That in Photoshop
It's a common refrain. You may have used it yourself when things don't go quite right while out shooting: "Don't worry. I can fix it later in Photoshop." Ah, but can you? Are you sure you really even want to?
You're probably already aware of the fact that there are limits to what you can fix. If the highlights were completely burned out in-camera, there's nothing there but pure white in the image. No amount of exposure adjustment after the fact can bring back what isn't there anymore. No fancy adjustments with curves, levels, blending modes or other magic tricks can rectify things when there's simply no useable data there to adjust.
Yes, there is a lot you can remedy, at least when shooting raw mode. White balance can be freely optimized since it exists in the first place merely as an instruction to be applied during conversion. Change the instruction and you change the appearance of the resulting image. Some white balance is going to get applied anyway. You merely changed the choice of which one.
Warming filters, cooling filters are mostly obsolete when shooting with a digital camera for this reason. Your camera can do the same thing for you without an extra layer of glass to shoot through. And so long as you're shooting raw you can make the same adjustment on your computer while seeing the affected image on a much larger screen than on even the best camera back. But the effect of polarizing filters can't be replicated digitally. If you didn't remove the glare in-camera with a real polarizer your image will be left with an unsalvageable white glare. And then we're back to the "no useable data there to adjust" problem.
Other changes can also be made to the degree you can stretch and push around the data you have to work with. Raw data is quite malleable due to its linear gamma color space. So long as you have viable data, you can do quite a bit to address issues related to hue and tone.
Some problems are related directly to limitations in current camera sensor technology than they are to errors made by the photographer. There're only so many stops of detail a sensor can capture. Every new generation of sensor that gets invented the story gets better but even this many years into the digital revolution the limitations we have to live with are severe indeed. The world around us varies from deep black to blazing white far beyond the means of cameras to capture. Sometimes the only problem with an image is that it's just not possible to create that image. High Dynamic Range image techniques can save the day by allowing you to digitally merge multiple different exposures to create the image your camera wouldn't let you capture. If anything moves between those multiple exposures you now have a different problem to solve though.
This is where things we reach the slippery slope where we risk creating an image that never was. If a flower or blade of grass moves between consecutive exposures you can no doubt justify fixing that since those exposures beyond the first likely wouldn't have even existed had that first exposure given you everything you need. And cloning out a cigarette but probably isn't the worst digital editing sin either since you just as easily could have picked it up on location had you noticed it. But what about removing annoying tourists who happened to walk by at the wrong time? Or moving a tree slightly to the left to create a more balanced, pleasing composition? Clearly it depends on what you intend to do with those images but it should at least give you pause for thought about how far is too far in terms of fixing things.
I've heard another saying to the effect that if you're good enough at Photoshop you don't even need a camera. Some artists are indeed quite adept at using what Adobe has provided. I've seen images created solely on a computer that arguably look better than real life. That is until you stop and think about the fact that they aren't real life.
I mean, the very reason why such a scene is so compelling is because it is real. We know that nature is out there, and the image serves as a reminder that this is so. It touches at a memory deep within us of something we all used to know firsthand but now may have gone neglected among the many commitments of daily life. The image represents something significant to us even if we've forgotten exactly what. If the image were nothing more than itself, it might look nice, but it could never have the same meaning to us in our heart of hearts.
Perhaps these days the refrain is changing to "I can fix it later in Lightroom" but the while the tools of choice for many photographers has shifted, the problems inherent remain the same. Some problems can be remedied, but many can't. And if we go too far the results could never really be the same. Even if the appearance is so good no one but the photographer who shot the image can tell the difference, that one person matters, at least if that one person is you.