Chairyavandan (Chitya vandan) is a form of worship where faith and humility are offered to all 24 Tirthankaras through the Logassa Sutra. In some Jain traditions it is performed by reciting two rounds of Logassa. Here is the simple reason:

• The Logassa Sutra itself is a praise of all 24 Tirthankaras. In many chairiyavandan practices, a shorter portion is recited for practical reasons, but some communities choose to recite two complete or nearly complete rounds of Logassa to ensure reverence to all Tirthankaras is expressed more fully and to deepen the act of humility and purification. This two-round approach is a matter of local tradition and ritual practice, not a fixed doctrinal requirement. Different Digambar/Shwetambar communities may have slightly different syllabi for how much of Logassa is recited in chairiyavandan, including whether two rounds are used. ( jainknowledge.com)

• The Logassa Sutra itself begins with invocations and names of the Tirthankaras, and the practice of reciting it (even in two rounds in some settings) centers on honoring all arihants and the dharma they show. Here is the sutra text as found in Jain sources: logassa sUtra … arihaMte kittaissaM, cauvIsaM pi kevalI … (and the following stanzas), which is the core of the logassa recitation used in chairiyavandan. The meaning is to revere the Tirthankaras and to bow to the Jain dharma and its teachers. ( jainknowledge.com)

• If you wish to know the exact line-by-line meanings and the precise variations between Digambar and Shwetambar practices, those details are given in authentic Jain sources and community traditions. The basic idea remains: two loggassa rounds can be a fuller homage to all 24 Tirthankaras, though some traditions shorten the recitation for the ritual's duration. ( jainknowledge.com)

You can read more about the Logassa Sutra and its use in chairiyavandan here