Question: how to avoid loading a package?

I do not like to load a package using with() and then use its commands and functions, since I then lose track knowing from which package a function or command being used in the code came from when I look at the code later on. So I like to write

pkg:-f() or pkg[f]() instead of with(pkg); f()

This seems to work most of the time, except I just found a case where I am forced to do with(pkg) at the top. Here is the example. I'd like to know if there is a workaround where I can avoid with(pkg) in this case as well:

restart;
f:=t->piecewise(t<0,0,t>=0 and t<z,t,t>z,z):
r:=convert(f(t),Heaviside):
r:=inttrans[laplace](r,t,s);

Now since Maple does not know what z is, it could not fully evaluate the result above (I can handle this with assumptions, but this is just an example). So now I replaced z by 0.5, but since laplace is not loaded, it still could not do it:

r:=subs(z=0.5,r);

So now I had to load the package, just to simply the above expression:

with(inttrans);
r;

This all becuase the expression earlier was left with only "laplace" in it, and not "inttrans[laplace]" as I typed. (why this happend, I do not know).

My question is: How would you do the above, without loading the package? I really do not like loading packages as I said, and like to keep the name of the package attached to each function to help me know where each function is coming from.