Ubiquitous (format-prompt) ?

[Gabriel]

Many places do not use the new 'format-prompt' function introduced by
commit 0985c0e6c6f1da712d3a48fa88af2861bf218d60, relying on a hardcoded
value of "(default %s)". So before opening any patch, I would like to
know if 'format-prompt' should be used everywhere, when applicable, or
if there's some rationale or exception to use a hardcoded value instead?

If we go ahead and replace everything to use 'format-prompt', how can we
deal with 'read_buffer' on 'src/minibuf.c'? That's the only occurrence I
could find on a C file.

By the way, here is the full list of occurences of grepping "default %":

./test/manual/etags/el-src/emacs/lisp/progmodes/etags.el
./lisp/filesets.el
./lisp/mh-e/mh-mime.el
./lisp/mh-e/mh-seq.el
./lisp/mh-e/mh-utils.el
./lisp/mh-e/mh-letter.el
./lisp/mh-e/mh-gnus.el
./lisp/ses.el
./lisp/subr.el
./lisp/minibuffer.el
./lisp/gnus/gnus-sum.el
./lisp/comint.el
./lisp/emulation/viper-cmd.el
./lisp/textmodes/reftex-index.el
./lisp/obsolete/vip.el
./lisp/obsolete/tpu-mapper.el
./lisp/obsolete/rcompile.el
./lisp/obsolete/terminal.el
./lisp/term.el
./lisp/international/mule-cmds.el
./lisp/progmodes/etags.el
./lisp/progmodes/project.el
./lisp/progmodes/cc-styles.el
./lisp/progmodes/xref.el
./lisp/progmodes/verilog-mode.el
./lisp/progmodes/cperl-mode.el
./src/minibuf.c

References:
1. https://debbugs.gnu.org/cgi/bugreport.cgi?bug=12443
2. https://lists.gnu.org/archive/html/bug-gnu-emacs/2020-08/msg02674.html

Regards,
Gabriel