any information on how what schema complexType constructs are mos t prevalent?

It seems to me that whenever I see a complexType it is almost always a
straight sequence. any studies done on this, any ideas why sequence is more
prevalent than other constructs (if you think it is)

One benefit I've noted in using sequence is it allows a push method of xslt
development, however I doubt that people would be thinking that far ahead in
their validation choices.