In fact, it depends not only on the artistic instinct of the author, but also on purely utilitarian things:

Numbering is preferred:

• If the sequence of items is strictly defined: steps in the process that follow one after the other are listed, or items are listed in order of importance. The number “1” means “first,” the number “2” means “after that,” and so on.
• If the list contains more than 5 items. If you put shootouts in a long list, then it will be difficult for the reader to “catch” the beginning of the next paragraph with his eyes. Just as it is difficult to count floors in high-rise buildings, where everything is completely identical from floor to floor.
• If the name of the list contains a number, for example, “4 signs of effective leadership”.

The numbered list hints that the sequence of items was not chosen by chance, and there is some meaning in it. The numbering looks like a more strict, exhaustive enumeration. For example, this list uses numbering because the order of items depends on their importance and frequency of use.

The paragraphs in the table of contents of a presentation should always be numbered to more clearly show the sequence of sections (an exception may be the table of contents of the presentation and the parallel structure and the table of contents in the form of an outline).

Shootouts are good if you need to emphasize the equal priority of items (or their simultaneity). Also, shootouts allow you to simplify the perception of the second level of the list, replacing double numbers like “3.2.” or “6.3.” on neat dots and squares.

The use of letter designations of items in lists – a.), B.), C.), Etc. – now occurs less and less, with the exception of some traditional cases (for example, designation of answer options in tests and questionnaires).