One of your point is that three things to memorize is more difficult than having just one, but sometimes it's just not the case: adding vivid images and funny/s

One of your point is that three things to memorize is more difficult than having just one, but sometimes it's just not the case: adding vivid images and funny/silly backstories actually makes remembering easier, as research suggested and borne out by personnal experience. Now, it could be argued that these images/backstories could be made up for random ASCII chars too, but to me it's just easier to do so with words. Regarding screenlocks, I tend to use relatively mediocre passwords (nothing stupid, though), since screenlocking is only useful against very casual attackers -- someone skilled and motivated will just get in if they have physical access to the box. But I agree that it's where muscle memory would work best.