Having such frequent sex would reduce the sperm count for subsequent ejaculations.
Most couples would find it quite exhausting to have sex so frequently day after day! Furthermore, after you have sex, there is a time where it is impossible to have another orgasm and ejaculate again. This is known as the refractory period. The refractory period varies widely between each guy and can last anywhere from minutes to days. If a man is having such frequent ejaculations, it would lead to a significant reduction in sperm count during subsequent ejaculations. Hence, instead of having sex 2 to 3 times per week (remember it is not per day!) when a couple is trying to conceive is sufficient.