I think it can vary a lot between people. Here are some examples from around the site:
A pattern that can be used in rooms:
Full example:
Related topic: Anyone here who has experience with The Vaughn Cube?
(If your palaces have an uneven number of locations, there’s also an alternate way to keep track of location numbers, but it requires a second set of images: How to Keep Track of Memory Journey Locations | Art of Memory )
Here’s an example of using 50 locations in a room:
Here’s an example of using something as small as a bar of soap as a memory palace: The Efficiency of Different Card Memorization Systems - #21 by Boris
In contrast, the book, Rhetorica Ad Herrenium, suggests not making the locations too small or too close together:
Again, it will be more advantageous to obtain backgrounds in a deserted than in a populous region, because the crowding and passing to and fro of people confuse and weaken the impress of the images, while solitude keeps their outlines sharp. Further, backgrounds differing in form and nature must be secured, so that, thus distinguished, they may be clearly visible; for if a person has adopted many intercolumnar spaces, their resemblance to one another will so confuse him that he will no longer know what he has set in each background. And these backgrounds ought to be of moderate size and medium extent, for when excessively large they render the images vague, and when too small often seem incapable of receiving an arrangement of images. Then the backgrounds ought to be neither too bright nor too dim, so that the shadows may not obscure the images nor the lustre make them glitter. I believe that the intervals between backgrounds should be of moderate extent, approximately thirty feet; for, like the external eye, so the inner eye of thought is less powerful when you have moved the object of sight too near or too far away.
It might be worth experimenting to see what works best for you. 