Back when we invented spears (okay, sharp sticks) the primary use was as a throwing weapon. That puts an upper limit of about 2m on any spear that is intended to be used one-handed with a shield, and even then it'd be awfully unwieldy to use in non-massed combat. If you want a pike or spear that is too long to be used one-handed, then you quickly find that it might as well be extremely long, because then (again when used en masse) you don't need a shield--your opponent is held at bay by the forest of pikes.
Regarding the OP, I would actually say that there are few, if any, real world examples of actual two-handed spears being employed with shields.
For a while there was a nice rock-paper-scissors thing going with cavalry-pikemen-archers in Europe. A gross oversimplification but there is some truth to it.