IF proficient with the skew, finish with the skew. However, if not, a sharp scraper will do on harder woods or woods that have been stabilized.
JT showed great wood to wood segments without sanding dust contamination. I often do brass or aluminum between segments of wood. Brass and Aluminum will contaminate from sanding but by using a sharp scraper, the wood/brass/aluminum can be brought to very smooth without the need for sanding also. Scrapers do not do so well on soft woods though, so stabilizing as mentioned earlier is a necessity.
There is a second way that "bleeding" takes place. I have not had a problem with bloodwood next to holly when using CA, but if using an acrylic finish or if I mess up a finish and use acetone to clean the messed up CA finish off, it will cause bloodwood to weep over onto the holly or other woods. Some have and probably a few people still do use liquid acrylic, devolving acrylic plastics in acetone for a different kind of finish similar to CA. These have caused bleeding between segmented woods for me. Stay away from acrylic finishes or acetone on certain woods.
The pens below were not sanded on the wood; I built up a thick layer of CA and sanded the CA, but sandpaper did not touch the wood. IN that case, the silver dots were silver solder. Silver solder smears like pencil lead when using sand paper. So the scraper was the only way for me to accomplish that.
http://www.penturners.org/photos/images/940/1_30_Pieces_of_Silver.jpg
If you care to read a little more, below is the time I posted it and the problems I ran into. It was a good while ago (2008).
http://www.penturners.org/forum/showthread.php?t=38213&highlight=30+pieces+silver