[gentoo-user] Options for "emerge"

[Dr Rainer Woitok]

Greetings,

some time back it was pointed out on this list  to only use  "--changed-
use" rather than "--newuse".  So I've meanwhile removed this option (and
also a few others) from my update script which I had created early after
installing Gentoo. It now basically runs

   $ sudo emerge --ask --verbose-conflicts --changed-deps \
                 --changed-use --deep --update @world

But if I understand the "emerge" manual page correctly, "--changed-deps"
causes a rebuild of a package,  if one of its  dependencies has been re-
build, even though the package does not require the newer version of the
dependency.  So does it really make sense  to have this option hardcoded
in a script?   Or does it just cause  plenty of package rebuilds without
any real effect?  Likewise, what about "--deep"?  Should I keep it?

Sincerely,
  Rainer