In the second sentence, you could omit 'in'. It would be the same. In the first, 'n times a day' (times a year etc.) is a fixed expression, and we wouldn't add 'in'.
cross-posted: adding this:
Habitual. 'May eat' is habitual, in the sense that it's possible every day. If the lion ate 40 kg of meat in a day, that was in one specific day, and is not the same as the habitual '40 kg of meat a day'.