Why this list decays
Because it produces no visible result. You check a signature, it says what it always says, and nothing about your evening changes. Repeat that fifty times and the check stops feeling like a step and starts feeling like a superstition.
Then one evening it would have mattered, and by then it has not been part of the routine for months. Nobody decides to stop. They decide once that this particular time is fine, and that becomes the habit.
The patternThe people who lose accounts are rarely the ones who never learned this. They are the ones who did it for a year, got comfortable, and quietly stopped.
each sessionTake the address from your listFrom a list you control, not from memory or a bookmark.each sessionRead the middleForgeries match the ends. Substitutions replace everything.each sessionCheck the signatureThe only step that settles whether you are where you think you are.each sessionRead what is being askedBefore you type anything, look at what the page actually wants.each sessionNote the dateOrder reference, window and message dates. It is the record later.
The realistic version
Two of the five are the load bearing ones: taking the address from a list you control, and checking the signature. If everything else fell off the routine those two would still cover most of it. The other three are cheap enough that dropping them buys you nothing.