But mainly on writes, not much for reads. And if your database is 99% reads 1% writes, the difference probably doesn't really matter. And tons of database ind

But mainly on writes, not much for reads. And if your database is 99% reads 1% writes, the difference probably doesn't really matter. And tons of database indexes operate on randomly distributed data -- looking up email addresses or all sorts of things. So in many cases this is not an optimization worth caring about.