Short answer: There is no single fixed number in the Jain scriptures for how many Logassa to recite on Mahavir Janma Kalyanak. It depends on the puja-vidhi followed by the sangh/temple.

• Shwetambar tradition: Most commonly 108 Logassa are recited during the Janma Kalyanak abhishek; some places do fewer or more (e.g., 12, 24, or 108) according to local vidhi.
• Digambar tradition: The focus is on 108 kalash abhishek; the number of Logassa recitations is done as directed by the conducting Acharya/Pandit and is not uniformly fixed.

For the Logassa sutra text and basics, see