BUG #15682: Change default value of checkpoint_completion_target to 0.9 for better performance?

The following bug has been logged on the website:

Bug reference: 15682
Logged by: Haoc Huang
Email address: hchuang95(at)gmail(dot)com
PostgreSQL version: 11.0
Operating system: Ubuntu 18.04
Description:

The [official
document](https://wiki.postgresql.org/wiki/Tuning_Your_PostgreSQL_Server)
recommends to set **checkpoint_completion_target** to **0.9**, which is the
more useful value and improves the performance.
"You can spread those writes out further, lowering the average write
overhead, by increasing the checkpoint_completion_target parameter to its
useful maximum of 0.9 (aim to finish by the time 90% of the next checkpoint
is here) rather than the default of 0.5 (aim to finish when the next one is
50% done). "

I wonder if the default need to be changed for performance concern. Thanks.