For what it's worth (2 cents), check lists ARE often too long. Seems 172 checklists are longer than a Boeing 737 to instill training perhaps. Of course, the 737 always had a copilot or non-flying pilot to do the read and the 'other pilot' to do the response.
So long, in-fact, when single pilot, they INVITE skipping a long checklist when an expedited take off is needed or one is in rough IFR weather on an approach and its too demanding to read a bunch of items, and then it is skipped entirely because a mental check list hasn't been learned and disciplined for every to/landing.
Thus, a disciplined, and specifically modified CIGARS and GUMPS carefully designed for the particular plane is very effective when teamed up with: no touch and goes (very bad for head training) and have separate warning/caution lights for the gotchas. Also, I add a 5 item "flow" check upon taking runway. If done each and every time (thus, no T and G) it works.
For example the C in my CIGARS contains 3 items: Controls, Camber (Flaps), Canopy.
Oh, and it's manly to say the mental checklist over the intercom; cognitive testing consistently shows how effective it is when you tell your brain something aloud.
A mental Landing checklist (aloud) definitely helps get the head outside looking and flying the airplane. Oh and it's 2 GUMPS for every landing.
One caveat is flying or training in many aircraft. Then it's DO THE CHECKLIST.
Maybe mental checklists aren't for everyone, and don't wait for the FAA to approve.
Jack Addison