Well, I would say make your judgement based on the final surface. A few strings here and there will happen on underlayers depending on overhang etc, but this is why we have top layer shell #layers (more or less). The final layers have to bridge the infill, the first layer of this is rarely going to look perfect but after at least 3 layers it should be mostly worked out.
You can always go to a smaller layer height or variable layer height to compensate.