Thanks for your reply. I have the same settings in those three files, except that I commented out the line in /etc/profile. The reason is this: in /usr/lib/man.conf I have
# Every automatically generated MANPATH includes these fields
If I leave the line in /etc/profile uncommented, then I lose these five paths, in accordance with man's man. And with it commented out, here's what happens:
bash-3.1$ echo $MANPATH
bash-3.1$ man -w
which satisfactory for me, but seems to contradict the manual. That is, when seeing MANPATH set and not empty, man shouldn't read /usr/lib/man.conf.
Anyways, your post puts it clearly, and that's good enough for me. Thanks again.