Fertilizers are not all the same and each of them is designed for a targeted use.
Fertilizers differ, first of all, in the content of the three main elements: Nitrogen (N), Phosphorus (P) and Potassium (K).
The need for these elements depends on many factors.
Normally it is said that a lawn needs 24 g/m2 of Nitrogen, 6 g/m2 of Phosphorus and 24 g/m2 of Potassium annually.

Simplifying we can say that in Spring/Autumn there is a greater need for Nitrogen (these are periods of vegetative growth), while in pre-Summer/pre-Winter , in view of particularly stressful seasons, Potassium must reign supreme .
A separate discussion is during sowing , periods in which the starter fertilizers will have an adequate level of phosphorus , useful for strengthening the root system.

The lawn must always be fed, which is why it is particularly important that the fertilizer guarantees release for at least 2/3 months.

Depending on the choice of fertilizer, the release can depend on the fertility of the soil and/or on how much water reaches the soil, or, as in the best fertilisers, depend only on the temperature (programmed release).