Do you think that you would really have difficulty differentiating between a mental image of Daffy Duck and a mental image of an actual real wild duck or a group of ducklings, (and for good measure a rubber ducky, and Donald Duck?)
Those are all very unique (at least in my mind), and I don’t see any difficulty in using all of them within a list…
181 daffy duck
170 ducks
125 donald
494 rubber
Those numbers / words could easily trigger those distinct “ducks” (using Major System rules.)
Unless I’m missing your meaning… Which is very possible!
This may sound like blasphemy coming from someone who passionately espouses the virtues of Major, but…
I think that the “best” 3-digit system from a structural/efficiency standpoint currently is probably @Zoomy 's Ben System, (or variations based on its C-V-C idea), because it is consistent in its construction and allows for a single syllable subvocalization when reading/encoding. The difficulty is that some of the syllables it generates don’t easily map to real words, and that they are just single syllables… You have to learn to associate them to full words/images and then learn to truncate them and recognize them just from the single structural syllable.
If I was able to go back in time to before I learned anything about major… I’d probably tell myself to just put in the work to learn Ben. BUT, as a gradual progression that can eventually get you to a 3-digit, 2-card system, I love how I worked up and kept building on the foundation of simple major.
I dunno, a long post to say maybe not all that much except I’m not sure how much there is left in terms of improving the process for 3-digit number encoding!
When it comes to similar objects, I know my brain fails if you just try to recolour them. A rubber duck is easily distinct from the mallards I see in the local waters, but a rainbow of otherwise identical rubber ducks get confusing very quickly.
Also, I’d just like to point out that Daffy Duck and a normal duck are among my 2704 images, and I’ve never dreamed of getting them confused - but different people’s minds work differently, so nobody’s wrong if they say otherwise!