I know we can’t put an exact date on it but there must be a rough time period when they fell out of common use. Maybe it was after 1964 because the silver was too valuable to use them? People wanted to save the new Kennedy? Ever seen a worn, circulated Kennedy half? Silver or non-silver? Not many. Was looking at some early WLHs today and am just amazed how many are in VG condition or even much worse. You’d have to think there’s a good decade or two of circulation on them. Maybe three or more? The WLH was a workhorse coin based on how many worn down examples you see. In 1916-1917 doesn’t look like many people set them aside as keep sakes.
Anecdotally I'd say they circulated fairly regularly at least until the late 70s. I pulled at least 4 1964 Kennedy's out of the till in the 74-76 time frame and even a well-worn Franklin. I had a pretty sizeable stack of clad that I spend in 1983 because I was broke, so those circulated then too.
