Moderators will step in if necessary. Additionally, not all questions get migrated. That depends if the closers are in the right mood, see it fit on the target side and do have a migration path available.
Cooking questions is an extreme example, those questions would be closed as off-topic without migration (no migration path available), downvoted, maybe flagged and most likely be deleted the moment a Moderator sees them. If a user keeps asking those questions, he would collect downvoted, flagged, closed and deleted questions until a mod steps in or he gets banned from asking further questions, whatever comes first.
Edit: I mean, there's no balance to keep and no problem to solve here. The community sorts such things out as they go. If a user keeps asking those questions, he'll have a rattail of angry users on his back in no time which will jump on every question he's asking until he's got enough and gives up, a Moderator steps in or he get's banned from asking further questions.
The community is a powerful tool which keeps to sort such things out on the fly without the need to step in. The simple and basic rules are defined here on Meta, they get extended and modified as needed and the community acts upon them. Off-Topic questions are off-topic, will either be migrated or closed. If a user tries to abuse that system, I'm sure we'll have a topic about it here on Meta.