I think you are referring to changing the forward lean of your boot, not cant. The bolts that adjust "cant" (really called cuff alignment) moves the upper cuff side to side, whereas forward lean is fore/aft. Without getting too far into it, only have a boot-fitter adjust your cuff alignment. As far as the forward lean is concerned, you can play with that a bit and not mess a ton of things up. But honestly, if you are not experiencing problems with your boot-fit, don't mess with it. There's no sense in changing it for change's sake if things feel ok. It would suck if you started having problems because you messed with either your cuff alignment or your forward lean or both.
If you do have fit issues, changing your cuff alignment or amount of forward lean can often help with specific problems. But if you don't have fit issues, don't mess with it.