One thing I always wondered: how do these codebases pan out in terms of maintainability? Are there J/K/APL programs with many programmers working for many years

One thing I always wondered: how do these codebases pan out in terms of maintainability? Are there J/K/APL programs with many programmers working for many years on the same code, with people joining and leaving the project? Do they continue to follow the same terse style that is beloved by most users of these languages?