The standard lens requirement for shooting events/weddings seem to be a combination of 24-70/28 and 70-200/2.8, I read both are nailed to a pro's camera 90% of the time (though I have problems doing the maths :-))
I disagree with your basic presmise that 24-70 and 70-200 are "nailed" to wedding photographer's SLR's...and are "must-have" lenses. This is simply not accurate.
One wedding photographer I know uses his crop body and just two EF-S lenses and has a bag full of speedlights and radio gear ...he looks through my L lenses and smirks... "so, more toys I see?" Another is an old timer who can pick his L-lenses from his oversized bag, but what sticks out in my mind is not his lens collection...but what he said about the amateurish need for razor thin DOF of f/1.2 on every occation...to paraphrase:
"You want a DOF where the bride appears to stand out amongst
her guests, not so shallow a DOF that she apears to stand alone at her own party; it would be rather sad and a terrible waste of effort to have invited all those people!" (P.S. This gentleman also uses for the bride's portraits a softfocus prime 135 f/2.8!!!)
So it is almost a cliché to say that wedding photographers "must have" 24-70 f/2.8 or 70-200 IS II. In fact, f/4 or higher would serve better at many moments. For portraits and "beauty shots" probably faster lenses ranging in f/1.2 to f/2.8 work best, but a wedding is more than just portraits.
Many wedding photographers worth their salt and established in their business would have several speedlites well placed and programmed ahead of time across the hall and will also want some background DOF so it doesn't look like the couple is on their own.
Just my 2 cents.