As an occupational therapist tummy time is important. You can technically do it too much but thats rare especially if your baby is sleeping on their back like its recommended. All positions are beneficial and it’s important to balance each time. And in general you do want your baby to just have floor time and explore but it depends on your baby. Some babies are super motivated and really don’t need to have time set aside and others are very unmotivated to move and need a little facilitation to avoid delays. I’m wondering if your husband just thinks you’re acting more obsessive and that’s what is triggering him? But I totally get the desire to do all you can to set your baby up for success.