The main concern is at the perimeter, and even then a little lace lift is still hard to detect. For the rest of the scalp it isn't necessary to do a full head bond but in areas where the scalp is exposed you want to get the knots as light as possible. The lace won't really be visible but unbleached knots will cause a grid effect that can be seen. It isn't something that people are going to pick out from a distance but it can look a bit odd up close.