Linus Torvalds [off-list ref] writes:
Yeah, I don't think there is any reason to really support it. If you have
more than a few heads, you really do need the graphical version to see
what is going on, and git-show-branch doesn't buy you anything.
The real reason it uses a bit per given ref is what it wants to
show is different from what gitk shows. It wants to show which
ones are reachable from which head on each commit -- in gitk the
user has to follow the line to find it out.
However, to track 300 branches, you would need a terminal with
360 columns or so, _and_ you have to count columns to see if a
given commit is reachable from the ref you are interested in, so
it is not useful at all in practice to do more than a handful
refs at a time.