Not all installations of internal cables are equal.
A number of things will effect how your groupset performs.
Not all components or frames are designed equally well, thus the cable routing in poorer designs will increase cable bend inside or encourage silly bends at the points of exit.
Some people just dont have a clue about how long to cut the outers and end up with some absurdly long outers which spiral all over the place, others with silly short outers which mean you have to bend the cable a lot.
By case of an example, my TT bike, the frame IMO has very well thought out internal routing, with good points of entry and exit, just as you might expect on a Cannondale. However, a combination of the tri-bar design and the person who installed the cables leaving the outers too long (not myself I might add) means that my front brake feels very much, off, or on, or very on, whereby the rear break feels nice and smooth and progressive.
Cable bend has a noticable effect, you dont have to have right angles or crushed outers to notice it, its noticable long before that. If you cant notice it then you either dont know what you are feeling for, or your cables are installed okay, at which point you can pat yourself on the back!
