We asked ExpressO authors about the last paper they submitted:
How many publication offers did you receive?
Examining this data by season reveals no significant difference between Summer, Spring and Fall. In other words, authors who submit in Summer can expect just as many offers as those who submit in Spring and Fall. In practice, there appear to be three, rather than two, submission seasons.
One Step Beyond
If you would prefer an ample number of offers to choose from, consider this fact: authors who receive at least 6 offers submit to an average of 80 law reviews.