"Giving Tuesday"

I've gotten dozens of pitches for donations from various nonprofits today, on the theory that today (following Thanksgiving Thursday, Black Friday, and Cyber Monday) is supposedly Giving Tuesday.

Is it really effective, though, for groups to send out their pitches on the same day that lots of other groups are doing it? Wouldn't it make more sense for each to try to do it on some day when it doesn't think the targets are already being asked by lots of other groups? I might well be missing something here—this isn't my field of expertise, and it is the fundraisers' field of expertise—so I'd love to hear others' thoughts on this.