There is an interesting Bonmot in the german Text the link above leads to ...
"15 Blendenlamellen formen bei Offenblende kreisrunde Unschärfeplättchen,
die das Motiv dezent unterstützen aber nicht beherrschen."
Roughly translated, they claim that the 15 aperture blades of the lenses iris
will form circular shaped circles of confusion ... wide open (!!).
I mean ... even in cheap lenses with 5 aperture blades the iris is exactly circular
when the lens is wide open ... so I do not see a need to emphasise this additionally ...
at least not for the wide open case.