For example, in CVs, I remember seeing some people talking about themselves in the third singular subject form which I believe made the CV sounds better because it reduces the selfish Is in it.
In the case of a CV the subject "I" is understood. Repeating the subject over and over again would make for tedious reading.
I managed a team of three people.
I developed a new organization scheme.
I doubled company profits.
The subject can be droped when it is clearly understood. A CV is all about one person. It's like saying, "here is a list of things I did:"
Managed a team of three people.
Developed a new organization scheme.
Doubled company profits.
There are several other instances where the subject is clearly understood and can be omitted. It's not really "formal" or "informal".
Thank you Neal