Compensated Saddle and String Gauge

[Bobisadrummer]

Are compensated saddles designed with a certain gauges, most likely Light (12-53), in mind?

[MC5C]

Yes, but they aren't typically designed for very accurate intonation in the first place. Often they are a straight saddle placed on a simple angle - guaranteed to have most strings out. Then you get a straight saddle on an angle with additional compensation for the second plain string - a lot better, but the third wound G string will be out for sure. The you get a two piece saddle so the first and second strings are good, the wound G string and probably the low E string is good, but the fourth and fifth strings are a bit out, because a correctly compensated saddle for all strings is never a straight line, the low E string needs a fair bit more compensation that the A string does. And as you suggest, it's quite dependant on string gauge, and not only string gauge as published, but the diameter of the core wire of the wound strings, and the action height you play with. By far the biggest reason that compensation is needed is the string bending effect from pressing the string down onto the fret. And no builder can guess what you're going to do, and most people can't tell anyway, so we're back to a simple straight angled saddle with maybe some added compensation for the B string. The expectation, and I think it's a reasonable one, is that if you need perfect intonation you'll do it yourself, because knowing that it's needed and that it's out implies knowing what to do to fix it, or that you have access to a very good technician that knows what to do.