>>21851824I finished the E4 around the 20 hour mark, which isn't exactly 'short' by modern game standards, I should note. That's pretty average, and there's still plenty of main story left, even if it's post-credits.
As for whether or not I rushed it, I may not linger over each area and catch each pokemon because I intend to come back later with the Super Rod, Dowsing helmet and Dive so that I can be thorough about it.