There is no such number as the ideal for every people. Just like it is enough for some to eat once a day, while others need five or six meals, it cannot be determined either how much sex is needed for a balanced life.
The sexual needs are affected by diet, medications, certain diseases, stress or mental state in general, as well as the relationship itself. When both of you are appreciated and supported, and both of you have someone to talk with about your problems, then your sex drive is probably higher than if you are isolated and lonely. But how frequent do people have sex with an average sex drive?
Luckily, there are people and institutes that do not spare on time, money and effort to answer these questions. This is why we know it now that the most people only have sex once a month. It might be a shockingly low frequency, but in our busy world, almost half of the people cannot spare time for an hour or less of pleasure, but believe me, more than 10% of the population have even less time and energy. They only have sex a few times a year.
The least people are in the group that has sex at least four times a week. They are less than one-tenth of the people who participated in the study of the Kinsey Institute. Back to the average couples, the rest of the people state that two or three times a week is their average.
So, we can conclude that 80% of people have sex one to three times a week. If you have a lot less or a lot more, then there might be a problem, but you might just be in a stressful period.