As long as possible it is better to keep const visible. It improves code maintenance a lot (no guesswork to see if this method changes my arguments).

If I see lot of arguments in a method, it forces me to consider creation of project based jaron (Matrix, Employee, Rectangle, Account) that would be much shorter, easier to understand (eliminates long list of arguments to methods).

In an extreme case, const can also be shortened into a project's jargon:

void drawShape(const Point &a, const Point &b, const Point &c, const Point &d, const Point &e) { } 

with this type of declarations:

typedef const Point CtPoint; // or with c++11 using CtPoint = const Point; .... .... void drawShape(CtPoint &a, CtPoint &b, CtPoint &c, CtPoint &d, CtPoint &e){ } 

As long as possible it is better to keep const visible. It improves code maintenance a lot (no guesswork to see if this method changes my arguments).

If I see lot of arguments in a method, it forces me to consider creation of project based jaron (Matrix, Employee, Rectangle, Account) that would be much shorter, easier to understand (eliminates long list of arguments to methods).