Hmm, interesting. TMTOWTDI is great for a small (one person) script, and One Way is better for a large (multi person) code base? That seems very plausible.
I think it is rather more related to team size than codebase size, really.
Think of how much can be done with a small group of people who all speak the same dialect / lingo. If everyone is on the same page WRT code style, then TMTOWTDI is just the magic that allowed you all to arrive on the same stylistic page.
Perl 6 is much better than Perl 5 in this because some of the styles that ossified in the Perl 5 dinosaur brains are truly grotesque to behold when deployed in the 21st century.
The downside of TIMTOWTDI is that the next person that comes along might not be as familiar with the alternate way you chose to implement something, which impedes understanding. That's never really an issue for a single person program, since they had to understand that feature it to initially write it, meaning they should understand it when they encounter it later (the vast majority of time at least. Forgetting skills from long ago happens).
Think of how much can be done with a small group of people who all speak the same dialect / lingo. If everyone is on the same page WRT code style, then TMTOWTDI is just the magic that allowed you all to arrive on the same stylistic page.
Perl 6 is much better than Perl 5 in this because some of the styles that ossified in the Perl 5 dinosaur brains are truly grotesque to behold when deployed in the 21st century.