I'm curious to where you find the "correct" way to install a cotter pin. Not to pick nits, but as a former A&P a lot of the aircraft repair manuals prefer the cotter pin install with one leg bent over the end of the shaft (bolt flat) with the other way optional. But I see your point where going perpendicular would indeed fill the openings and prevent any movement. Alas we may be beating the proverbial dead horse.
2014 Ram 2500 Bighorn CC SB CTD 4X4
2016 Flagstaff 8528IKWS Platinum
2013 Keystone Hideout 23RBWE -Sold