So I tried some more now, and with a pipe wrench or a baseball bat, it was about 5-10 hits (I guess depending on the starting condition of the window). Seems a bit odd that it takes up to 10 hits to break a window that way when all it takes is one hit if you right click and select smash window?
And yes, if possible, it should be made much easier to get the "smash window" option to appear. As it is now, it seems that you need to stand in precisely the right spot and also have some luck, because the dialog option doesn't appear consistently.