I have actually been overwhelmed before in individual rounds by marine drop pods. I still wasted everything, but at times I had issues with target priority. My own shooting phase the first couple turns was very limited and quick
Note its a standing rule of mine to give every unit that can take it early warning override and I play suit heavy. So yeah dropping in the middle of my army with only 3 or 4 drop pods isnt a great idea, even with dreadnoughts.
My advice is not to drop spread out. Drop on the edges so the opponent cant use multiple units shoot you with maximum effectiveness and you can use multiple units to shoot up his fringe units.