This is a personal practice that also varies depending on the ski models and / or the quality of the snow. Some do not round, others little and others more and this on different lengths. In general, we avoid rounding skis slalom and personally I do not round in heel even when it comes to longer skis.

For snowboards, it is advisable to round the front of the edge "front side" about 15 cm.

Also look question “Is it necessary to remove the lip with an eraser after using the Roto Finish for sharpening the edges of skis or snowboards?”