I rambled on about acoustic guitar intonation a while ago and mentioned that sometimes, the proper intonation point for a particular string falls somewhere fore or aft of the actual saddle. In some cases, all of the instrument's other strings do likewise and this can be an indication that the saddle slot may be in the wrong place. Often, however, it's just one outlier. One lonely string, steadfastly blazing its own out-of-tune trail. An intonation maverick, if you will.
It's not always a big deal. Perhaps it's just a little out or, perhaps your ear/brain isn't particularly bothered by it. However, if you're one of those cursed with tuning-sensitive ears or if your poor, perfectly-pitched brain screams in discordant agony when you play certain chords or intervals, you might want to consider drastic action like this.
Well, it's not terribly drastic, really. I've made a new saddle for this tenor guitar from a bone blank and all strings except the third intonated quite happily. The delinquent string wanted to intonate miles away from the saddle.
So I extended the saddle.
There are a couple of options for this but the most straightforward is an additional piece of bone that's been glued to the rest of the saddle. It's half the height of the saddle itself—it lacks a 'bottom' half and it actually rests on top of the wooden bridge so it's completely reversible (just pop a new saddle in). It gives me the additional scope needed to shift this string's intonation point forward.
Looks odd but sounds much better.