We always do touchups, no concrete floor is perfectly flat and the saw’s height can’t be changed on the fly. Sure, we could just make deeper cuts, but as any homeowner with tile knows, deep grooves in the floor accumulate dirt. We avoid this by making light, shallow cuts (no more than 1/8” on average) and wherever the concrete dips we come back with the handheld grinder to finish it off.
A big advantage diamond blades have is that they make smooth cuts and last very long compared to abrasive style blades. Imagine starting at one end of a cut and watching the score line disappear as you went along because the blade had worn away.