I'm sure almost all of us had a situation where you shorten a trunk or cut of a branch and you face a huge wound. On conifers this is not such an issue but on deciduous trees scars are often an issue and dont compliment the overall design
Often we make compromise and don't heal the wound, some don't know how to heal them and there are even some who don't even try and leave them like they are.
OfBonsai magazine published a great description of the "Van Meer Technique" which I think is a great way to heal wounds and huge scars on deciduous tree. The technique was developed by Hans Van Meer over the last 15 years.
Definitely a must read article :)