Non-resident employees who exercise employment in Singapore for 60 days or less in a calendar year may qualify for an exemption from Singapore tax on their short-term employment income. The exemption generally does not apply to company directors, public entertainers, or professionals such as consultants, trainers, or coaches. This tracker uses days in Singapore as an estimate; IRAS rules are based on days of employment, which may differ from physical presence in some cases.
https://www.iras.gov.sg/taxes/individual-income-tax/basics-of-individual-income-tax/tax-residency-and-tax-rates/working-out-my-tax-residency