http://revach.net/article.php?id=1666

Section: Halacha   Category: Tshuvos
Noda B'Yehuda-Minchas Yitzchok - Who Will Be The Sandak? Who Will Be The Kohen?
The Minchas Yitzchok (9:54) says that it is not proper for a person to buy an Aliyah for the same Kohen every single time. The Gemara says that a person who gives all of his Matnas Kehunah to the same Kohen brings hunger to the world.

The Noda b'Yehudah says that just as a person should not give all of his Matanos to the same Kohen so too a person should not use the same person as a Sandak for all of his sons. The Minchas Yitzchak concludes from this Noda b'Yehudah that it is also not proper to always buy an Aliyah for the same Kohen every time.  

Disclaimer: We try to convey the Tshuva to the best of our ability. We admit that our understanding may not be accurate. Please also understand that this Tshuva may not be the final word on this topic. One should consult a Rav before drawing any conclusions.