No it is not the only way. I do think it is unquestionably the best way though. Yes, it is absolutely the standard for tank shots. Not only tank shots, all types of photography really. There is no excuse but ignorance not to use it IMO.
I'm not sure how RAW "adjusts white balance"... Which was the question.
Lightroom has some intuitive features/functions that allow you to manipulate white balance easily, as do many other programs, but I use/know LR so i'll speak to it.
The results are better if you are working on a RAW file vs a JPG. This is because the JPG has data has been modified, by your camera, to a specific white-balance, where the RAW file has a white-balance setting that is calculated/applied, and therefore can be removed or adjusted... the JPG has already "modified/damaged" the pixels so you are not working with a "good" copy.
I do not believe there is a "fits all needs" process for adjusting white balance, even with something as specific as a tank photography, but generally this is the process I follow.
My process is;
1. Shoot the shot
2. Get it into LR
3. Adjust the Color Temp till it "looks good to me"
4. Adjust the Tint "till it looks good to me"
5. Check very carefully the entire photo for areas that have suffered adjustment difficulties, and fix (sometimes in photoshop, sometimes in LR)
As for the "looks good to me" part, specifically I take the color temp/tint sliders and SWING them madly from one extreme to the other... as I do this I watch the areas that are most effected and get a feeling for exactly how these sliders are modifying/adjusting things... then I go back to the origional starting point and tweak things towards whatever "correct" setting i'm looking for.
Having a calibrated monitor is important, if not critical, and calibrating your printer (if that's your target end-results/format) is also critical, other wise you've no real sense of what your doing other than on that specific monitor, for those specific settings...