Of course, giving out promotions to employees usually varies on the company too, so it shouldn't only be on duration at the company tho like I said achievement should matterOf course, this is a valid point for employee promotion. If he or she does something that increases the value of the company, as you describe a great feat, he or she deserves to be considered for promotion.
Of course, there are different criteria to consider when thinking about upgrading an employee. Both their performance and their skills, among other important qualities. These are traits and profiles to be valued.