Go Navy.. I believe Michael is speaking of the saddle height at the bridge. In other words the distance from the top of the bridge to the bottom of the string.Depending on the angle cut in the saddle top, the strings contact more or less of the saddle as they cross it. With any pre-cut saddles, there is a narrow window for the string to contact the entire top of the saddle. The slant of the saddle in the bridge allows good intonation w/maximum contact.IMHO the more string on the saddle, the more energy transfer = more sound.
When I build a saddle from scratch, I first fit the entire blank to the slot.Then I radius the top of the saddle close to where i believe the action needs to be leaving the string bearing surface flat, but the length of the saddle top radiused to match the fingerboard.(on my personal Taylors, I go 14" instead of 15" as I tend to hammer the D and G strings)
Next, I string the guitar and note any necessary action or radius modifications. I then make these modifications leaving the top of the saddle flat,w/all the strings breaking on the front edge of and contacting the saddle across it's entire width.The strings come off again after noting where intonation adjustments need to be made. After these adjustments, it's restring and fine tune the intonation.Then I angle (relieve) the back side to get a good string angle out of the pin hole w/maximum string contact on the saddle crown.Sometimes with a low saddle, I slot the bridge, as much as possible, so the string is free from the bridge plate to the saddle without stressing the actual saddle. The slot ends up kinda rounded inside the hole.
Then comes final polishing to the desired luster. The last thing I do is "bone" the bearing surface of the saddle. I do this in the vise with a piece of 440 stainless steel rod(the bone) that has been polished glass smooth.(You can use glass). I repeatedly rub the top of the saddle w/the bone until I feel it's as smooth and hard as possible. By doing this the strings don't leave as severe marks on the saddle and those annoying little squeaks and rubs are all but eliminated. Boning is an old wooden baseball bat technique, and another essay entirely.
A good piece of bone or ivory prepared this way will actually last 20+ years without any need to replace it. I've seen old Martins, that w/a neck reset could have retained a 40 year old saddle.
And that's how S MS Picker builds a custom saddle. It's not cheap, but quality never is.