The core principle
Supporting documents should prove the visa purpose—not simply fill upload slots
ICA's live eVisa system publishes different document requirements for different classes. A multiple-entry business applicant, for example, is asked for a passport biodata page, a PNG business invitation, an employer or sponsorship letter and a return airline ticket. By contrast, some simpler online visitor classes require only the core application, fee and passport biodata page unless additional evidence is requested.
That means “all visa types require passport photo, return ticket, cover letter and bank statement” is not an accurate universal rule.