think of it like this, imagine a professional businessman is reading your comic and his boss is watching over his shoulder
when do you think giving people a heads up as an inappropriate page is about to come up is a good idea?
I think its passable for pages with swearing totally passable for a not needed warning unless the swear word is drawn in big shining glory like:

FUCKING SHITBAGS!!!!


ya might need to put a warning that its about to come up
unless the swear word is really lowkey and no one will notice it like:
click here
(Fucking shitbags.)
then it's not needed as much
you don't want the businessman to suddenly scroll down and see an unexpected giant swear word while his boss is watching.