In Jain Śwetāmbara tradition, different tilak shapes are used because they often represent sampradāya, temple custom, or devotional symbolism.

Common reasons are:

1. Tradition of the sect

- Different Śwetāmbara groups, temples, and sādhu-sādhvī lineages may follow slightly different ways of applying tilak. - So the shape may vary by local custom.

1. Symbolic meaning

- Tilak is a mark of bhakti and śraddhā. - Shapes may be used to symbolize purity, reverence, devotion to Arihants, or remembrance of Jain values.

1. Temple or ritual identity

- In some places, specific shapes are used during pūjā, aarti, or temple visits. - The design helps show the ritual style being followed.

1. No single compulsory rule

- Jainism does not require one fixed tilak shape for all Śwetāmbars. - It is usually a matter of custom, discipline, and tradition, not a core doctrinal necessity.

1. Respect for different practices

- Because Jain Dharma values anekāntavāda, different approved practices can exist within the tradition. - The main purpose remains inner purity, not external display.

In short: Śwetāmbars use different tilak shapes mainly due to sampradāyik tradition, temple customs, and symbolic devotion. The outer mark is secondary; the real emphasis is on inner bhakti, ahimsa, and purity of conduct.