Pixel Art Tutorial Series is currently the most popular thing on my page. The idea behind this is to take suggestions from the community and try to make a tutorial out of these things, helping out fellow deviants along the way. You can also find my pixel art tutorials in groups like #TutorialsForYou, #TutorialsClub and #PixelCommunity. Here is a list of tutorials in my Pixel Art Tutorial Series, tutorials which are underlined and bold are already ready tutorials that you can read, other tutorials without the underline are tutorials that will be posted in deviantART in near future. You can also suggest new pixel art tutorial series by commenting on my profile page, on these tutorials or by sending me a note. Enjoy!
Let's say that you have a very detailed artwork where you have same color in many different places and all these areas are only couple of pixels wide or are just long lines between other colors. In this case paint bucket is quite useless because it would only paint couple of pixels at the time. But with this method you can hold your mouse button and drag all over the area and it will paint only the color you selected and won't paint the other areas.
So, if I'm well understanding, Brush paint would do the same thing. Your method is good for only one colour on large areas. But if you want to change the colour on one line, it doesn't work. Or if your eraser is too big for the zone, It doesn't work either.
No, actually other way around. It is very good when you have to change a color on small detailed areas like for example lets take this cube. With this method you could for example change only the border color without having to worry about other colors next to it. You wouldn't be able to change the border color with one click if you'd have a paint bucket, but you can do it with eraser.