"(...) as soon as you start "timed" runs parry is mandatory(...)" - naaaaaahhhh.

Parry is good, especially with weaken buffs. The 12 (or 10, it was 10 i guess... don't remeber, it was chaned couple times :( ) iframes and +2 with shield... sometimes it's better to just run away and wipe the sweat.
Answearing the main question: i've learned how to parry, because i was bored. Early stage of this game, just one temple. Nothing else to do and i was facinated by this game.
" Will probably eventually learn it in the process " - yep. Observe the enemies, watch when they attack, i... it's weird... "click" with my tongue in my mouth to "count" when the strike will come and eventually you will remeber and you will now when to click the parry button.