It is not true that the more you shower, the cleaner your skin is. On the contrary, showering too frequently may lead to irritated, dry and cracked skin. Furthermore, each person has different skin chemistry. No two skins are alike. Each of us has our own cocktail of skin bacteria. Some people sweat a lot, some have greasy skin, etc.
Until the use of hot running water (and hence the ability to take a shower) became widespread, bathing required heating water in basins and transferring it to the bathtub. It was common to use the same water for the different members of the family to bathe in. It was important to try not to be the last... Doubtless, the shower has improved personal hygiene (at least in developed countries). A shower a day, in the morning or in the evening, seems to be the most common average. But in order not to damage the external layer of skin cells (the stratum corneum) and the lipids (fats) that keep the skin hydrated, we should not use very hot water. In order not to alter the pH of the skin, we should use a gel or soap with a pH between 4.7 and 5.5. Another important detail is not to dry oneself with towels that are too harsh and may scratch. And, finally, it is a good idea to use a moisturizing cream.