if you can 100% prove continuity within any of the shows crossing over, be my guest
there are plenty of examples that i could use to disprove it, and I mean spoken proof rather than soundtrack sampling.
I could use, iron man in hulk and hulk in iron man references
hulk in fantastic four and ben grimm in the hulk references
doom in spiderman, fantastic four and hulk references
or thor in the fantastic four and also thor in the hulk
not to mention the varying designs for the hulk in his own show, fantastic four, iron man and seen in clippits of the x-men.
i won't even bring the surfer into this but there is no evidence from his own show that he has contact with doom or the fantastic four previously.
in none of the twelve instances there does anyone show any involvement to anyone from another show previously. Nor our any of the events covered referenced and again, there is no viable timeline or chronology.
I don't know what you wish to show to counter this, it's fairly conclusive but feel free to do so.