Depends on what you’re trying to achieve… if you’re just concerned with short numbers, say less than 100 digits, then there is no reason to change.
Personally, I’d say that @SilvioB’s argument here should be your deciding factor. The advantage with a true 3-digit system is that images are 10x less likely to repeat. I say “true” because adding an adjective doesn’t make a 2-digit system a 3-digit system.
If you converted 357 into milk or 726 into kanji you’d have a true 3-digit system. By simply adding an adjective to your image: 065, 165, 265, …, 965 will all be some kind of jello, which is still as repetitive as a regular 2-digit system… just 10 different kinds of jello.
Are you using a memory palace at all? From what you’ve written for the two numbers this seems more like a story method or are you in fact storing four items in the same location? If it is in fact story method, you should upgrade to memory palaces before upgrading to a true 3-digit system.
This is probably true for most people that don’t compete in memory competitions. In speed cards for example it doesn’t make much of a difference how often images repeat because you’re just dealing with one deck. However, if you have to do 1 hour cards at the world championships repeating images are not very helpful when dealing with multiple decks of cards.
So unless you’re trying to go for say the IMM title for which you have to do 1,000 digits and 10 decks of cards in an hour, there is probably no reason to upgrade to a 3-digit system.
I’d agree 99% with that statement, because there are certain advantage using an overlapping 3-digit system when memorizing pi, but only if you want to be able to do the Everest:
That said, even with a three digit system, I still use OO on four locations for credit card numbers for example as they come in the form XXXX XXXX XXXX XXXX anyways. The security code I do as a 3 digit separately.