timestamp - timestamp result

I regularly see people suggesting to use

extract(day from one_timestamp - other_timestamp)

to calculate the difference between two timestamps in days.

But I wonder if the "format" of the resulting interval is guaranteed to only have days
(and not months or years)

The following:

timestamp '2020-06-26 17:00:00' - timestamp '2019-04-01 14:00:00'

returns an interval like this:

0 years 0 mons 452 days 3 hours 0 mins 0.0 secs

However, is there ever a chance that the expression will yield the (equivalent) interval:

1 years 2 mons 25 days 3 hours 0 mins 0.0 secs

e.g. as the age() function does.

Is it safe to assume that "timestamp - timestamp" will never contain units larger then days?

Thomas