While at first I had a similar issue, I did find that re rolling a code until no digit repeated, then having it show and read off digits for like 3 minutes where I focus specifically on on codes that I know has at least 1 correct digit and the other 2 digits are wrong (for example say I set the code to 573, when trying to forget the code after I set it I will look at the screen for any code that has a 5 anywhere in the code while listening to it ramble off random numbers as well, so for about 2 minutes I will read codes like 539, 857, 511, 583, 835, 275, 045, 556, 581, 559, 915, all of which have a 5 somewhere in them, then I will focus on every code for about 1 minutes more, then for 2 minutes more I will focus on all the codes that have a 2 in them, 273, 721, 912, 228,012, 852, etc and after about 5 minutes of listening to random numbers and intentionally focusing on a single number for 40% the time and a totally wrong digit 40% of the time it makes forgetting where that single number was in the permutation easier as well as forgetting the other 2 digits easier as well.

I'm not saying it is a needless feature, just saying there are ways to make it harder to remember the number even if you have excellent memory. Doing such makes it so you will forget the order of the numbers and you will know that either there is a 5 somewhere but not a 2 or a 2 somewhere but not a 5, with a 3 digit lock that still leaves you with about 600 possible numbers out of the original 1,000 so while does eliminate 400ish numbers is still pretty effective.

(And yes I know a 3 digit lock is pretty quick to get into, but that is what the OP mentioned, plus that is currently what I have because I have not found a 4 digit one in stores and I am not sure the exact MM diamiter fits into my cage so better to buy it in person rather then on Amazon unless I find out the diameter.)