Question

My son Yekutiel Yehuda, may his light shine brightly,
has reached the age of 13 and become obligated in the commandments—mazal tov.
 
He also often goes up to lead the prayers as the prayer leader.
In our area there are a few overly nervous people,
and they told him that if he leads Shacharit, Mincha, and Ma'ariv consecutively, he has to say “without a vow.”
I told him that in my opinion this is exaggerated nervousness, because:
1.
It does not depend on him; rather, he is an agent of the congregation. If they want, they appoint him; if they do not want, they do not appoint him and appoint someone else. So this has nothing to do with his taking on a personal good practice.
2.
This applies only to an established and recognized custom; someone who joined in casually should make a stipulation. But something that is not known or recognized anywhere as a common custom does not fall under the category of a good practice done three times.
And there is no known or recognized custom of regularly going up to the lectern for one who has no obligation to do so.
 
Am I right?