Ryujin
Legend
Mounts aren't too bad but animal companions are going to seriously screw up the flow. The more decision points characters have, the longer each one's turn will take. Effectively double the decision points and I don't care if it's an Encounters session, a home-brew, or a canned maxi-adventure. It's going to be a mess, unless the animal companions in question are clones of Steven the Iguana, from "Your Highness."
If you explain this to your players, giving them the opportunity to rebuild and avoid the issue, you may find that you have far less trouble.
If you explain this to your players, giving them the opportunity to rebuild and avoid the issue, you may find that you have far less trouble.