It's not as true for softies and maybe a little truer for LPS not as true for SPS.
Sometimes it's not too bad to have some kind of residual nitrate value.
That said though I still prefer low to zero readings because a reading is really more of a balance point. A nonzero value tends to mean something is produced faster than it is consumed (or exported) which means there could be a trend in the number so it still bears making some effort to keep it manageable.
