There are 2 problems with console channels as implemented.

1. Drivers/boards do not always use the channels in a consistent way.

2. Any channel defined in include/console_channel.inc takes up flash space for the data structure (and associated descriptive string). However, it is difficult to remove unneeded channels, partly because of 1: the minimum set of configuration options that may lead to a certain channel being used may be very large, and lead to unreadable ifdef statements.

https://chromium-review.googlesource.com/c/chromiumos/platform/ec/+/1070948/1 takes out the low-hanging fruits, but there is more that can be done.