The optimal dimensions for making and curing hot compost are cubic. However, it is easy to write “cubic”, but often very difficult and impractical to keep cubic dimensions.
Note that the volume of the pile after the first turn (a few days after it is turned and allowed to settle down) is usually between 60% and 80% of the original pile’s (original) volume. And after the second turn, it will probably be as little as 50% of the original volume.
Any effort you can make to keep these successive piles, cubic (or nearly so) will be rewarded by a higher quality compost, more broken down, more “mature”.