Realistically if you're doing a max breath-hold, you can only really do one of these per session and only a few times a week. Now, if you want to improve, you need to do enough training volume, which means multiple breath-holds per session, session after session, week after week. So by only doing a max, you're not doing enough training to make the necessary improvements; therefore, you need to drop the intensity so that you can do enough breath-holds to allow you to make the adaptations you need.