Is this "save practice" (setting default font scale)?

[Arthur Miller <arthur.miller@live.com>]

For few years now I have been using this to set default font height
in my .emacs, as told by Mr. Eliz some few years ago in some social
media thread:

(add-hook 'after-make-frame-functions
            (lambda (frame) 
              (set-face-attribute 'default nil :height 160)))

This also seem to be THE way to customize fonts as found on numerous
SX/Reddit/blogs/etc discussions. So far so good.

I have refactored my init file and trying to push some things to
early-init to save some load time. What I have found is that above
little code adds ~200 ms to the init time; take or give.

Maybe it shouldn't but I have profiled several times and it always add
to startup time.

Furthre investigation discovered a giant list of faces in Emacs:
face-new-frame-alist. Setting corresponding value in face vector for
'default seems to achieve exactly same, but without measurable
difference at startup:

(aset (cdr (assoc 'default face-new-frame-defaults)) 4 160)

So my question is, is this safe to do, any pitfals I am not aware of
(more then me poking into internals which may change in future)?