How often one should eat is an individual matter, but here are some guidelines.
Note the times of the day when you usually feel hungry and have time to eat and try to arrange your meals then if possible.
In many occupations, mealtimes are set at a fixed time and you are forced to have your meals at that time.
Most people are satisfied with two or three main meals and a few snacks. Many people with eating disorders go without food during the day and guzzle down food later in the evening. This increases the risk of compulsive eating, but the risk can be avoided by not going without food for more than four hours. Eat some fruit if meals are delayed.
Eating a proper lunch and dinner every day reduces the risk of eating any kind of food without caring about its nutritional value.
A problem for school children is that they sometimes are compelled to have lunch too early in the day, and as a result they eat almost nothing because most of them are not hungry. Later, when they are hungry, there is no food for them, so they satisfy their hunger by eating sweets and buns. It would be better if school lunch were scheduled at a later time.
Some people enjoy a big breakfast and others cannot stand to eat in the morning. One scientific study showed that children do better in school if they eat a proper breakfast, but a later study showed that this only applies to undernourished children.
A question which is often discussed is whether it is better to have fixed mealtimes or to eat only when hungry. A solution which usually works is to have fixed mealtimes, but adjust the times and amounts to one's own hunger and satisfaction.
To eat well is an art. The body must be well nourished and furthermore one should feel content but not overstuffed after eating.