It also depends on the steel and heat treat. Of course the steeled edge will not be as strong as a freshly sharpened one with the bur removed. On some steels however this is more or less a moot point unless the blade has been repeatedly damaged and steeled back many times. The basic goal of steeling though is to maintain a usable edge without actually removing metal, which is often not necessary if the damage is small enough and the steel isn't weakened.
The sort of damage that steels (of the sort talked about here, smooth steels are preferred to grooved ones, as grooved steels are basically files) can fix are rolls and dents, IE: deformations caused by contacts with hard objects/ twisting in wood, etc. If you tag a small rock, or after chopping some hardwood your edge has some rolled spots you can usually push them back with a bit of work on a steel, as opposed to grinding away the damage. Chips have to be sharpened out. It is always a good idea though to recut the edge with a good sharpener from time to time , so that fresh unfatigued/unrusted steel is what you do all your cutting with.
